Granted, starbases can negate the nova's effect, but you still lose the up grades, or at least i did.
No, actually, if your planet is bombarded to 0 HP but still has a starbase protecting ownership loss, you do not lose your planet upgrades.
YOU have oveusly never been sova rushed
I have been Sova rushed many times. And I've successfully defended myself against it many times as well, once I understood the strategy.
just sayin' I did on my first 3 games and desided on tec then
Deciding on which race is the overall best to use after only playing 3 games is a bit hasty, I think. 
ALSO TEC HAS GREAT ARMOR. the vasrii can cut through shields in the advent defences like a hot knife through soft butter. Also park you marza on the edge of an astroid belt outside the grav-well as far as it can go with a starbase in the middle. 9 times out of ten the other guy doesn't even see the marza, just the few starbase gaurds, [akken, hoshikos, etc] It might just be i find my way into a pack of noobs but the computer does it too, soooooo.
If you're playing someone who lets you park your Marza on the edge of a massive fight while leveling up to level 6, you're playing against a poor player. If you're playing in a game where building a Argonev in an asteroid belt is viable, your opponent is probably quite bad as well. If your opponent charges headfirst into the starbase in the asteroid belt and loses their fleet so that your cap can level up, your opponent is extremely bad. And factoring in whether the AI falls victim to the strategy should be irrelevant - it's like saying you can beat a 5-year-old at chess.
I'm not intentionally trying to be hostile, but the fact is that competitive games are quite different from what you seem to be thinking they're like. Even getting a capital ship up to level 6 is hard.
the flack on the hangers
That's definitely a plus. Doesn't tilt the balance in favor of TEC though.
and the abilitys on the guess cannons can make a mean defence, espshaly with a resuppling starbase and repair platforms, mabey a few hoshikos in a near by well to deal with a kostra shot.
Wait, you think Hoshikos are sufficient to deal with a Kostura?
...Seriously?
...
The strength in the Kostura cannon lies in its ability to create a phase stabalizer node at the target planet, allowing the Vasari player to warp in their fleet directly, bypassing heavily entrenched front lines. A single Kostura shot can decisively decide the game in favor of one team or the other.
ALSO i have found that the kol is useful early too if it comes as a 3rd cap ship.
If you think the Kol is really that useful early-game, you clearly haven't been playing against decent players
The Kol's GRG is only marginally useful in slowing enemy caps, its Adaptive Forcefield means little when decent players will be focusing on attacking other ships, and its Flak Burst is only worth the Kol's cost when there are tons of strike craft on the field already.
Late game Vasrii= TEC[if spaming]...
I take it you've never seen Howthe? in action late-game...
Keep in mind I'm talking about games against decent opponents (that is, on ICO). If you're thinking about what the strongest race is in games against noob humans or against the AI, tons of strategies work, from any race.