Flying races maneuverability
Unfortunately, most of the fliers are the same. However, there is one (and only one) that really stands out. Unfortunately (part two), that flier is Silver Surfer.
He turns much better/tighter than the other fliers, and I want to say his top speed is also higher, even without boosting. Before I had him, I'd fail air races constantly, but then when I use him, I can clear them with 10-15 seconds still on the clock, no problem. I can even miss rings, turn around, get them, and still win with time to spare.
The downside is you'll have to finish his quest chain in order to get him, and step 1 of that is winning against him in an air race on the Helicarrier. His missions afterwards are all simple past that point though, there's no more air racing required.
Since this is a race vs. an NPC, you could try to block him from taking off by parking a helicopter in front of him, although this is going to be somewhat difficult as he's riiight on the edge of the carrier. If you want to try this "strategy," talk to him to get the mission started, go to the helicopter call in point, get a helicopter, and land it on/in front of him, then start the race.
I didn't use this trick, I beat him legit, although it took several attempts. I found that I could eventually beat him with Iron Man, but it takes some practice with the controls - you have to be able to fly pretty precisely in order to make this work. The hardest part for me was the transition between hovering and flying, as it changes the controls significantly.