If you don't live in base I would HIGHLY recommend the 737 or Airbus. If you can avoid the 756 do it. I got hired into the 756 as a new hire and I spent the next 3 years on reserve. It doesn't sound like you might know what that entails so let me explain a little.
Reserve means your essentially on call for roughly 18 days out of the month. All reserve starts out as a 12 hour call out so hopefully you at least live 12 hours away. That means if they call at 8 at night you better have some way of getting there at 8 in the morning which can be hard sometimes with flight schedules. I'd say around 30-50% of the time though you'll be converted to a short call which is a 2 hour call out. Which could mean a lot of flying back and forth from home to be in base for the call. Anyway you get the picture, commuting sucks, and commuting to reserve is awful. Pick the most junior fleet for where you want to end up to spend the least amount of time on reserve. That's just my opinion but I believe many will agree with me.