I have. It is called Starcraft (even Wh40K: Dawn of War)

I think Birth of the Federation also comes close. Unlike SotS in Botf not all sides get access to all tech(yes I know about the sadomizer but you can still get any tech as any race). Romulans and Klingons are the ones that have cloak, Ferengi are the ones with huge trade network and so on.

But SotS is a lot of fun. I got it a few weeks ago when it was on sale on Impulse and I been having fun playing it ever since. Played a few games as Humans, and now tried Morrigi.

I do not know about you but I had situations where I needed to use my attack fleet for defense.

As for Sins, I must say that after playing SotS I cannot recommend Sins to anyone. Sins is a hybrid between SotS and Starcraft and both of those games are better (I played them all ).

have them both - but I prefer RTS games - since sins I've been looking for a game that was simlar and nearly as good -have not found 1 - love it

From my point of view on other hand StarCraft is too shallow and SotS is too complex and boring. Sins as a hybrid between these 2 is actually game exactly for me

SotS isn't that complex -- it is actually kind of simplistic in its own way -- it just has tons and tons of ship to ship combat with custom designed ships.  If this is tedious to someone, then yah they are gonna dislike the game. 

Hello auto resolve!

Though sure, taking more losses than otherwise may be annoying, but if you're in mop up mode, then you probably don't care about the losses that much anyway.

That and just research up the Xeno trees and send your colony data to your enemies, then demand their surrender.

It works, though usually you have to spank a couple of their fleets and or glass a few worlds.  Hitting their HW usually speeds up that process as well.

I find the pace better if you slam research and econ down in the 50%-75% range.  Slows things down, extends the DD age, and generally makes you appreciate the little things that much more.

SotS destroyers are 30m long tin cans.  Do you want those to be the most common ships in your fleet?  Of course, if you're playing the Hivers, AM-era DE swarms are deadly since it is a swarm of cheap, easily replaceable, tough, fast, well-armed hornets.

No.  You just need a lot more and better missiles than you previously did.  A PD-armed vessel won't be too bothered by a couple missiles.  However, if you send a few MIRV Missiles and a swarm of regular missiles, all with micro-fusion engines, their PD will have issues coping.

Oh also, who the hell plays with random events turned on? They drive me completely insane.

ex situation: "awesome, after much struggling and death, I've finally managed to take out this enemy planet and setup a colony of my own; next turn:Oh awesome, my newly founded colony has been destroyed by asteroids/sentient machines/slavers/etc."

I dunno, random events are one of those things you at least have an option to tune to your liking.  I don't mind them, they add some variety and occasionally a challenge.  Hell, if you've never played a big enough or long enough game to run into the Puppet Master, System Killer, Peace Keeper, or the Locusts then you've missed out on quite the challenge as well as the whole OMGWTF!!!! factor they cause when they first appear.

As to the issue with smaller ships being obsoleted.  Two points there.  #1, there is always a use for some sections not available on the larger ships, though sure, you probably don't base your fleet around those ships (there are exceptions though).  #2, you can slow research/econ and make the DD era last longer.

Hell my last game I was Morrigi in a barred galaxy with a Zuul empire out on the tip, and me inbetween them and the center.  This was a problem, because the Zuul had only one way to go, and that was through me, so I had to jump for some weapons techs sooner than I wanted to, but I found (well I kinda knew already) that a mass of lightning emitter drones would chew up their lightly armored fleets, even through them hitting CRs.  So I packed my fleets of a couple dozen DDs and took on their CR fleets with roughly even loses, ship per ship.  But in terms of cost I was coming out way ahead.

Eventually though the strain on my economy started to get bad, even with as many trade routes as I could affordt, and when the Tarka who bottle necked my entrance to the central cluster decided he would rather go to war with me than continue our NAP I was well and truely screwed.  Even though I have CRs of my own, and a few more tricks too boot, there was no way my economy could handle the strain of a 2 front war, and since Tarkan ships are not made out of balsa wood, my fleet composition which held back the Zuul (and made some inroads in to their territory) was almost useless.  I didn't have the time to research up a proper counter and build enough of those ships to counter the Tarka, while maintaining the ship numbers I needed on the Zuul front.  I tried to stop, then slow the first real invasion by the Tarka, but they crushed my fleets and I barely put a dent in them, soon the colonies on that front were being burned, and I had not enough to muster any kind of defense against them.

Oh well.  SotS regularly kicks my ass when I set up a game outside of my comfort zone, and with so many galaxy shapes, individual AI player difficulty settings and boni, it's easy to make something easy or impossible based on your skill level.

Hmm, that was a bit of a tangent, but the point was that I used DDs almost exclusively through 100 turns of that game, I had a few CRs around, but they were too expensive to build and maintain, and were not as effective as a mass of DD drone carriers with a few PD ships thrown in to lessen the missile alpha strike.  Though by the time the Tarka were attacking me the Zuul had upgraded their missiles to the point where that alpha strike was starting to hurt.  Oh, and the advantage to upgrading missile techs is that you don't have to rebuild any ships to take advantage of it.  All missiles upgrade automatically.  So yeah, there's a hard counter to missiles, but the cost of using them is less because your old ships will upgrade (at least the missiles will) anyway.  Build a few early ships with plasma cannons and green lasers and they are stuck like that forever.  You either scrap them or use them as fodder.  Missile based fleets do not suffer from this issue as much, though clearly their engines don't upgrade so you need to keep them separate from your new fleets so that they don't slow you down.  Then again if you're a Hiver this really doesn't matter much at all.

Ahh, so many choices, so many paths, yes, Overwhelming perhaps, and not everyones cup of tea, but as far as the Space 4x genre goes, SotS gets more right than it gets wrong.  Something I'm hard pressed to say about the other contenders in that niche.

Never heard of the first one but sins is the scond greatest rts i have ever played other than supreme commander: forged allaince

Well I agree that GC2 burned out pretty fast for me, but I still fire up SOTS regularly and have a great time with it.

Not sure about 'immersion', I mean that's a bit nebulous of a term, and very subjective, but SOTS does seem to offer a vary wide variety of start up settings, and with the random tech tree, nominally means no two games will play out the same, because there isn't always that perfect tech path to domination.  More so because it really does matter what techs your enemies field, and if you need to go another direction as a counter to them, or if they go a certain direction as a counter to you.

The weaknesses of SOTS are still in the fleet management area I think, there are a lot of tools in the game to make this easier though, but sometimes it's just annoying shifting new production to the front(s).  Guess you can just play as hivers though, then this is completely a non issue

Well my guess about this immersive quality you are looking for, you should play Birth of the Federation then

I played that game for years just because it would immerse me in the Star Trek world each game as each of the 5 sides played differently and similarly to the series.

Another game that was very immersive was  Dawn of War games. The artistic style and all the little animations and cool abilities of the troops just kept me coming for more.

And of course Starcraft universe, with superb characters and great story as well as really unique fractions captivated me the most.

SotS will be a "one more turn" game, at least until you hit the end game phase where your empire is bigger and more technologically advanced than everyone else's.  When you've gotten that critical mass, it becomes a grind as your superior fleets have to drop enemy worlds one by one.  Fortunately you can research their language and demand their surrender.

Well I believe there is a demo for SoTS, but I don't know what version of the game it is.

The most recent (ANY 1.80) is far superior to anything pre ANY, for a variety of reasons.

None the less, the demo of even the base game should give you a feeling for how it looks and what it feels like.  Just that it's missing a full 33% of everything else which has been added in the expansions.  Probably more than that 33%, but that's taken mostly from the additional races which are available.

Anyway, I would strongly recommend the game if you like a robust, yet simplified economic/development model (this isn't civ in space) with a very detailed ship design/combat model (this is HWesque).  The quality of the 'lore' is also excellent, though honestly, I don't care one bit about it, but it is well done, just not something which matters to me.

Granted, once you start sand box games the lore doesn't play much of a role anymore (compared to some scenarios), though you still have races which are easier to get along with, or harder, based on the lore.  Otherwise immersion... yeah, you start with one colony (you can set this to more if you want to start bigger) only basic tech (again, you can set this to more if you want), and a huge (or small, you can set how many stars/opponents you want) galaxy to explore/exploit/exterminate.  Your immediate decisions on what to research, which planets to prioritize (money vs. industry unless you are lucky to have systems with both), how big of a defensive/offensive fleet to maintain, how soon to go on the offensive, how soon to colonize the 'hard' worlds, how to deal with the random menances which pop up, how to do diplomacy, ...

Perhaps you should head to the Kerberos forums and read some TARs.  Some are better than others, but that's probably the best way for you to get an idea of the immersion others have found.