Yeah, whatever. GT just isn't that great. It started the whole GT clone craze (obviously) but it hasn't been the best at it since Sega GT on Dreamcast.
Sega, btw, isn't currently the king of anything other than shitty Sonic games.
I could go into huge detail as to why Forza completely destroys GT as a simulator, but if you were enough of a car nerd to understand the incredibly nerdy car shit I'd be going into, then you'd already feel the same way I do about Forza. I mean, if you really want to get into it, we could, but that's a lot of f*cking typing for me. I will say though that Kazunori Yamauchi didn't even have a drivers license while he was making GT1, and the game plays that way.
BTW, I don't own a PS3, or 360, and almost certainly never will, but I have played the shit out of all these games and I've come to the conclusion that Forza 1/2 is not just the first good piece of software to sport the Microsoft name, but is totally incredible in its own right.