I dont think you can go wrong with either of them. Ive had both and both shot great but my Bart seemed to have the edge on my Brux tubes and cleaned up easier.
Flip a coin really. Never had a brux I but shoot with guys that do and they shoot great. Same with Bartlein's, although the reason I like bartleins is becuase they usually have better availability. Brux's not so much.
I'm losing count on the number of Bartleins I've used and have only shot out one Brux. I'd still NOT hesitate to use a Brux at all, it cleaned up easily and most importantly it was superbly accurate.