qvault's organic section was great practice in my opinion. Not sure what the negativity surrounding the OC section is about, but I just flipped through my OC/GC practice exams from qvault and I'd recommend getting both. That said, qvault as a platform has some POORLY worded questions, some I'd even go as far as saying were flat out errors. I've come across a few in the bio and OC sections, and have actually reported the errors to their server.
Don't have experience with qvault's RC, but if you have Topscore, I'd recommend doing all 3 tests. Topscore was the most representative of the real DAT in terms of passage difficulty level, although you won't get purely S&D questions like you do in Topscore, question format will be a mix of Topscore and bootcamp.