Most definitely more jobs opening up at a big hub. Probably less bull

at a smaller hub? That's been my experience anyway but, and I must stress this,
YMMV, and that certainly isn't a given!!! I had the same choice and went small, and it's a pretty chill environment that I 100% do not regret. Union and management aren't at each others throats here.
When we're shorthanded, the center manager will go come in and go dig out a long alone, not to hit some number, but because after the load positions are covered we only have one unloader, and he isn't about to solo 9000 packages out of 2 longs and 3 pups and get everyone else on pre-load off to school, other jobs, home to their kids, etc in time. And then at the end of the day will go ask the stewards to grieve the entire day on him so we can get everyone pizza and donuts and teach someone a lesson. HR I guess for continually dicking us around on new hires? Who knows. But it's appreciated. Not by many of the people here for reasons that are both quite valid and kinda dumb(depending), but that's the way everyone in our center wants it and it works for us. The big center around here is just a

show start to finish. And that works for some people too. ::shrug::
On the other hand, you can probably get "lost" in a big hub. You can't get lost in a small hub, and if it's a contentious place, good luck trying to stay out of it.