I recommend trying some on and if possible trying them out. That's not always possible though unless you're in an area to do so. There are a lot of good fins out there (wish I could have tried several of them) and most people will recommend what they use or have used.
My first pair were TUSA traditional long fins which I thought were fine, until my legs started hurting as I began to dive more. Read a lot of material about diving and leg pain and found that split fins might help. Bought TUSA X-PERT Zoom split fins without trying them first and on no one's recommendation. First time diving (and every dive since - 9 years) I've had no leg pain. I could recommend those, but others would maybe say you can't maneuver as well with split fins, so get something else.
My 3rd pair, ScubaPro Twin Jet full foot split fins, I alternate with the TUSA's depending on where I'm diving. I tried these on in my LDS and they felt pretty good. I only hoped they would feel as good in the water, which they did. I have also used both to snorkel with and they work fine.
Good luck on whatever you get.