Best comprehensive verbal course for non natives

If you are weak in verbal then 90% chances are you are struggling with SC portion big time.

Let me be honest, you will not be master or learn grammar per say but you will definitely learn almost all the concepts required for GMAT.
Course is well designed and categorized in orderly fashion - walks you through concepts one step at a time.
Audio is a big plus, it keeps you engaged and in between interactive questions make sure you are paying attention.

Of course, it's not a magic wand that you join the course and you will learn all or will get V40+. You have to put effort and explore a bit outside too. The course cover most of the things but you need to practice the concept learnt in different scenarios on different type of sentences, comprehensions and reasoning questions.

For those (including me) who use their ears for SC, e-GMAT presents a pretty well defined frame work. You can modify it depending upon what best suits you but you will definitely start using logic to choose answer instead of 'sound/ear'.

I was pretty comfortable with CR and RC, but still those two sections are as good as SC.

I can blindly suggest this to anyone wanting to score till V40. Above V40 it's your own effort no course can guarantee.

They have large practice question bank, Scholaranium, which can be customized too as per your own choice. Good way to track your progress.