I don't think it's a particularly important issue to dwell on. It will depend on the relative length of each finger (and thumb) on your hand, and that's a factor that won't be the same for everyone, by any means. There's also the amount of articulation available for those fingers. So how can there be any hard and fast rule?
It will also vary with how one is playing - gently or firmly. That will necessitate a difference in curvature/straightness - or at least it does in my playing! Watching world class players, some will play with lower wrists, straighter fingers, others the opposite. True, with fast runs, curved fingers are the menu for the day, but that's not what you ask.
The best way is what suits you best! At least you've addressed the 'problem', and come up with some alternatives. An excellent thing to do, when playing any instrument. As time goes on, your fingers will naturally find their best position - and that will vary with what's being played, and how it's played. It's similar to 'which fingering should I use?', and the answer there is the same. Whatever suits you and the piece in question best. I don't believe there's a one-fits-all answer.
Dvers - please explain why!!