Warner has a higher ceiling, he throws a ton and has great wides...but he could just as easily get injured and miss games. And if Leinart does decent during that time then Warner starting again might be iffy.
Eli Manning is a low end QB1 in my eyes, one of the last QBs you can start safely week to week. He's not great but his job is safe, and you could do a lot worse than him. And winning the Super Bowl might have finally given him the boost in confidence he needed to take his game to the next level.
So if you're forced to have one, I'd pick Eli since he's still a starting QB with decent options. With Warner I would need to make sure I have a good back-up in case of injuries.
Thanks to deluxe_247 for sig, he is welcome to sail with the Captain too!
I will win all of the fantasy cafe games.....next year