You have been given so much good information. Please try to rent or borrow as many guns as you can to try out,, to begin to experience the different traits of each type and caliber.

My suggestion is the one or both of two excellent calibers and that is the 357 or 44 mag. But I do this for 2 reasons.
(1) Is the vast variety of ammo available for each one. (hint) this can offer you a larger window of opportunities when hunting. Ex: a little varmint hunting.
(2) You can practice with some milder and sometime cheaper ammo than going full house mag cartridges all the time.

If you choose a 44 mag DO NOT Discount the 44 SP cartridge. It is sometimes referred to a s Gentleman's cartridge and rightly so. It will kill deer all day long and several other animals as well. It is mild shooting with little flash, and little recoil.

So much for calibers... When you do decide on brand and caliber be sure the trigger is good on your new pistol. Do not let a Butcher get into your pistol. One you make your purchase you can return here for more enabling Err I mean suggestions for a QUALITY GUNSMITH to do trigger work. I like a 2LB on the single action side.