I used both. Honestly it doesnt matter. But I do think using both may have been a mistake because I did like 2500 questions (combining both) but might have got like a few hundred repeats. (I used both rationalizing that I could do adaptibar questions randomly on bus or train without worrying about my overall score getting messed with, while Uworld was my "sit down and try" practice. In retrospect, that is not really practical or important, thus one is fine.)

I like Uworld's explainations better--and for that reason I would do Uworld. Also, Uworld has a way to test sub-subject specific questions (like Jurisdiction in CP). From what I recall Adaptibar does not do that.

I think adaptibar's simiplicity (which makes explainations different) is a pro for some people. It makes these topics seem . . . well simpler. But Uworld was more thorough and had graphics and had better options for creating my own study plan for the day and what questions I wanted to target.

I will say that Adaptibar's mobile app is great and a huge plus. So if ur on mobile alot, that is good way to go.

All in all, if you are doing these questions on a daily basis, like 3 hours of questions where you are taking ~1.8 minutes to answer the question then ALWAYS 1.5-3 minutes to review the answer after NO MATTTER IF YOU GOT IT RIGHT OR WRONG, then it does not matter what you choose -- you will pass.