I can't say I prefer one to the other but I'd have to agree with thunda to a certain extent...Wheeler has given flashes of what he is going to be in a year or two. When he's locked in he's an ace and I have no doubt he'll figure things out and have a great MLB career.
Syndergaard has looked like a monster in the minors and I personally think he is a can't miss top end of the rotation starter. When it comes down to it the spots in the Mets rotation will be superficial....Harvey will be #1, Wheeler will be #2, and Syndergaard will be #3..but the truth will be that on other teams each of them would be a #1 starter.
It will be more of a 1A, 1B, 1C with the Mets rotation...then of course you get to face Niese and Gee as the 4 and 5 who are honestly quality #2 and #3 starting pitchers. Assuming Harvey returns to form after this season and that Syndergaard is as good as in the bigs as he's looked in the minors...the Mets will easily have the best starting rotation in baseball.
Now just if they could figure out a way to improve that lineup