Either or would be good. The Smith probably has a better trigger, although you can slick a GP trigger up to be as good. I did that to my 3" GP 44 special and have yet to get to it on a 6" 357 i picked up in April. Definitely on the schedule when I get some time.
Hopefully that $900 Smith is a brand new gun, as that's the number for a new new in my area. Used, that laughable, and they'll have it awhile.
I recently picked up a 629-6 for $650. I gave it the best inspection I could in the store, and after it passed that I decided to take a chance with it. Trust me, I took it apart when i got it home, trying to find something wrong with it, but it turns out I landed myself a pretty fair deal on that. It's my first Smith revolver to boot. No endshake and good lockup, I'd probably take the chance with it.