Romo has outstanding numbers against the Giants... he really smoked them, especially early in his career. I don't have time to do the research right now, but I'd be surprised if anyone in league history has thrown more TD passes against the Giants franchise.
You are correct by far. However, I don't know that I would want to use TD's as the criteria, it wouldn't be fair to quarterbacks of other eras, before the rules were changed to give offenses incredible advantages, especially the quarterback.
For example, in Roger Staubach's days, there was no just thing as "in the grasp". The play ended when the quarterback was on the ground. There were no "helmet to helmet" rules. There were no 5 yard rules for the DB's, etc, etc.
Besides, isn't it the job of an NFL quarterback to produce enough scoring drives to win games? Shouldn't victories be the guiding factor in determining the best. Then there is also the factor of reliability, or lack of injury.
Tony is 11-10 against Manning and the Giants, including playoff games. We know he was facing Eli because Eli has never missed a game. That makes Manning 10-11 against Romo when you include the playoffs. I would call that a tie considering the importance of the playoff losses to the Cowboys.
The reason I brought up Roger was because, in this category, WINS VS LOSSES , at least ten games throwing ten or more passes, Staubach is in first place in NFL history in winning pct vs. the Giants at 16-1. Danny White is in 5th place at 9-2. Tony Romo is in 8th place at 10-7, Aikman in 13th place at 11-10, Don Meredith 14th at 5-6-1, Eddie Lebaron 2nd to last at 3-11-1.