Hey, I haven't taken the TIME gmat course, but I have friends who have taken TIME's CAT prep course. Although for GMAT prep, here are the courses that I found to be the best from my research:
Quant - TTP
Verbal - Egmat
Overall - Veritas Prep
I haven't taken the TTP or Egmat courses as I found out about them a bit later and had already started my prep with Veritas, which is also pretty great. You will definitely need the GMAT Official Guide for real gmat practice problems or you could use GMAT club as well. Check out this link
https://gmatclub.com/forum/abhimahna-s-secret-no-1-gmatclub-follow-functionality-257054.html to see how you can make the most of gmat club.
You can also check out the course review section on gmatclub to know about others experiences.
https://gmatclub.com/reviews/gmat_courses/?fl=menuApart from this, it also depends on how much time you have, what are your weak areas, what is your target score, and what was your diagnostic score.