You have to follow your heart, and drag your wallet along kicking and screaming
My first single action (not my first handgun) was in 45 Colt. It's a blast.
If you have any aspirations of loading black powder I would suggest the 44-40. It's a thinner case and seals much better than the 45.
But if you don't think you'll go black, then go for the 45. If you like single actions then you'll end up with the 44-40 down the road anyway. Lol
It's not a .357, but the open top revolvers in .38 special are cool little guns.
For a .357 I'd go Ruger and hot rod the crap out of it.
Do some research on how to properly hold a single action. It can make a big difference in comfort and group sizes. It's a different sort of beast. I love em, personally. I pour less lead down range and enjoy myself more at the same time.