Aside from stating a personal opinion about which you like more, I don't think 00 and SEED can really be compared. They both are essentially war dramas, they share a world filled with war and convoluted political situations, and have badass giant robots. The drastic difference between them is in the story telling. SEED is a purely character and emotion driven show. This seems to piss some people off, but I actually quite enjoy it, and think that the show's point can come across all the more powerfully for the over the top emotion that comes trough the characters. And the realism suffers a blow because of the same emotion. Like when a mobile suit suddenly gains enormous power way beyond its technical limitations and destroys some more powerful suit, all because of say, the anger its pilot was feeling at the time. Or, when a previously impervious ship suddenly can take huge damage from mere missiles, just so tension can be added, and the story line advanced. But thats ok, its the way it is, and no other anime (at least gundam anyway) has managed to make me so attached to the characters, story, or anything. And when I watch it, everything is present in such a way that it really lets me explore my own emotions and sort of bring a concrete understanding to a lot of ways that I view the world. Its easy to relate to I guess.
Anyway, didn't want to make this a SEED discussion, just pointing out some of the differences as I see them.
My opinion on 00 has been pretty much summed up here. And so far I think its an equally good story. Just not presented with such an intimate view of the characters. Still, we have been getting some back story, which is nice. Poor Setsuna... Pretty screwed up childhood that kid had :(
Also, despite the overall amount of realism the show has, I still think the Virtue is ridiculously overpowered.
Like in episode 15, when it blew that massive, miles long channel through the desert. Seriously,how the hell are you supposed get that kind of energy output?! Please get around to explaining these GN particles to us...
Um... Oh yeah, one other comment I wanted to make was on Veda. Number one, I doubt it has any connection with Shuhenberg. Unless of course it was another of his creations. And I think instead of being an AI (though that perfectly plausible) I pictured it as just an insanely powerful computer, built to analyze any data given to it, and spitting out all possible outcomes or something. Not necessarily an AI in other words. Just a really high end military supercomputer. But I'm sure we'll find out sooner or later.
And yes. The new Op/Eds suck >_<