I wouldn't put it like Eli has a Super Bowl ring and Tony doesn't. I'd phrase it, The Giants have a Super Bowl Ring and the Cowboys don't. (Speaking in terms of each QBs tenure with the team, of course)
For some reason a lot of you think that this is a 1 on 1 battle between QBs. It's not. It's 53 against 53 and THAT'S how you win a ring.
Remember that Eli plays behind one of the better offensive lines in the league. Not that ours sucks, but the Giants are called for far less penalties than the Boys are, which in turn hampers Tony's numbers.
I personally can't stand Eli, but I won't take away from his ability to play the position. He's a very good QB. but like most has his off days just as Romo does.
IMHO, I think Tony has the bigger upside. He has a scrambling dimension to his game that Eli doesn't. Eli has a knack for finding the open receiver and putting the ball on target. He may edge out Tony in that category. But I think Tony is able to extend the play longer and reacts much better while under pressure.
But to reiterate my point, you can't make your judgment based on a ring. You have to look at the individual dynamics of the player to make an educated decision.