TTP

I have took the GMAT 4 times, twice at home and twice in a test center, I went through the TTP materials twice in total and practiced in their portal for countless hours. I have tried other test providers practice questions, but have only used TTP materials.
While I have seen other materials, TTP is the only provider I have spent material time using as designed. I am a self-studier and need to "figure things out" on my own in order to retain them. This is the perfect match for TTP. Their modules are crafted to show you the concept and its logic, then lead you into discovering how is it presented in GMATland materials, and then to challenge you to think beyond the concept to answer challenging questions. Because of this structure, i encourage you to trust their process. I skipped around initially and over some concepts in total, only to comeback and do the whole program when my score was stuck in 710 and 720. The process works, don't chase speed it will come with concept mastery, complete the modules is practice for your practice.
TTP Verbal, a bit here since it was marker "Beta" when i used it, although by the end all the modules were released. I have to say that there were some YouTube series that I watched that framed the SC concepts of Verbal very well. Then with that framing the TTP Verbal really came to life. I did not ever open the RC and CR modules as I was already testing there at a high level.
TTP Practice Problems: These practice problems are not that similar to the official practice questions, but they are better practice. If that makes sense. You can see the concepts being tested and where the "trick" of the question is just like the GMAT Official questions, but i think the TTP are more clear. GMAT Official questions can be a bit more muddled, so it took some practice learning how GMAT tests different concepts. Other providers i used for practice (Manhattan and Kaplan) questions were far too "tricky". This is hard to explain, but it felt like they were trying to piece together random concepts in order to trick me, where i felt the GMAT would show you the concept and then test your ability to get to an answer logically and quickly.
Only ever use Official GMAT Mock Exams btw, none i have found are even remotely close to accurate representations of the real exam.