Well, I'm not expert, but I'll share what I think i know

Helical = better stabilization, work best for broadheads. More drag (because of more spinning) so lower down range trajectory. Strong helicals may not clear some rests easily (this point is null if you shoot a drop away).

Straight = less stabilization, but better down range trajectory. Will clear any rest easily.

Offset = a compromise of the two I would say, but that's about as far into as I can get.

This isn't very in depth, but I think what I said above is a good rule of thumb for each.

As for me, I use straight fletch. I want the down range trajectory for my 3D shoots, which is mainly why I shoot a bow. Plus, I never have a problem with broadhead flight with them. Since I mainly use field points I don't need a lot of stabilization.