I'll vouch in favor of Pastest. I've completed nearly 2000 questions since it was released in the fall. I've used them systems-based with our curriculum and more recently cumulative for step review (test in June). From use in systems, it's fairly pathology-heavy. I found it helpful though, because it drills down on presentations and pathophysiology well. Around 90-95% of the questions are associated to pages in 2016 and 2017 FA (without images). Most of the questions are solid in my opinion, definitely on par or better than medium/hard questions on Rx. Pastest is harder because they don't throw buzzwords at you or sneak mnemonics in the vignette. It makes you think deeper than you want to. A few questions come off as "strange" because they're picky or worded vaguely, but they're legit things you've probably been exposed to in school. Some require you to draw on very specific knowledge to differentiate drugs or diseases while some questions I only know because of the little details in my lectures that FA/Pathoma doesn't hit. It's the only place I've seen Castleman disease and it's association with HHV-8 virus (Kaposi sarcoma), but it was, indeed, mentioned in our lymphadenopathy lecture.
I admit my average is way lower on Pastest, so it can be frustrating coming from Rx. Also the explanations can vary in quality. A few are really basic but most have a learning objective and good commentary. The interface is different than Rx/Kaplan too but I got over it pretty quickly. It's been a great primer for test-taking strategy while grinding through the secondary banks (~1000 questions also finished in Rx). I'm glad I stuck with Pastest so far, but obviously I wouldn't sacrifice time in UW for it later on.
