The biggest factor to me is the co-driver. Some won't use the engine brake at all and make you roll around in the berth because they keep using the brakes, some talk way too loud on their phone. Others try to knock the kingpin off the trailer everytime they couple (remember you'll be sleeping through this much of the time).
The other thing that surprised me was how tight some of our schedules are. I have yet to cover a run that had much excess drive time built in. If traffic cooperates it's common for us to run 730+ miles in 11.5 hours then switch to the berth... A lot of drivers struggle to do that on a regular basis, but that's how guys I go out with run to make the $$. It's all about getting to the TA ASAP and getting on the clock while you wait on your loads.
Also, schedule is everything, if you're the B driver get with the most senior driver you can find who isn't a jerk.
Good luck!