It would be rare to find someone with both the Success One and STRIVE book because theyre essentially mutually exclusive. However I had the STRIVE Phys & Chem whilst my friend had the Success One Phys & Chem so I would probably say:
No of questions: STRIVE for Both Phys & Chem
Quality of Questions: Equal
Quality of Answers: STRIVE had some silly errors but also better MC explantions. So probably STRIVE is better
No. of practice exams: STRIVE for Chem, Success One for Physics
Overall I'd recommend STRIVE over success one. Especially if you can find a copy of success one from a friend or in a library and take some sneaky pics of the practice exams