GK is the best, and then Baze. I think Baze isn't that good without Chirrut. You don't want to run Shore with a Rex leader either, because his crit immunity defeats the purpose of a Rex lead to feed turn meter from crits.
I think StHan is getting bad rep here... he is a good tank. I would put him up there with Old Ben easy. With both Rex and StHan feeding your turn meter, you can get CLS and DN moving faster. You need to make him fast however! You need Rex above 220 and StHan as fast as possible, so you can get tenacity up and taunt early. Old Ben is good, but he also needs to be fast if you run him.