not to be too obvious but it sort of depends what you want to do. "sales/trading" is basically a sales job. you hold inventory but it is really just to facillitate client orders. the way to make the big bucks here is by having good clients not by being a good trader.
the prop shop could mean almost anything. i would argue that amongst those who know, susq is as well known as the big banks, and at some things is more highly regarded (yes, including GS). but there are a lot of prop shops and many are crap and many are unknown names.
so without knowing the actual bank or actual shop i couldn't say a lot more.