Dude rent everything and try it. I found that I really liked 45's and my first gun is still my p345. Never know. I shot lots of options before I picked though. 9's, 45's, 40's, 357's, 38's of all shapes and sizes. Find a gun that you can pick up and say "wow this feels really good in my hand" and then shoot it.
If you can shoot it comfortably(relatively if you never shot a gun before) and confidently(hella important!) then make a note of that.
I can tell you what I learned from searching myself.
40's have more recoil than 45's. The smaller the gun, the more recoil its gonna have. 357's hurt when they are fired from a small gun. If you pick up a revolver that shooters 38's or 357's make sure it can do both. some can only do 38's and thats no fun.
take your time. go slow, and really see what you say to yourself in your head before and after you shoot the gun. pretty much do your own reviews. Hell take a paper and pencil and make criteria for yourself.
Suggestions are as follows
weight, size, comfort, reliability(not really in a range gun, they are rarely cleaned), capacity, after market availability, aesthetics. some of these might rank higher or lower. its all up to you.
good luck and welcome