Kaplan is great. So is any other resource that gets the information into your head. It doesn't matter what other people are using. It matters what works for you. I liked free or cheap resources, and that is why I would have considered Kaplan materials to be too pricey.
I did end up paying for a video series that really helped me remember a lot of the more technical concepts and to apply them quickly and accurately. But mostly? I used free content outline that I found on a website to direct my study through whatever other resources I felt like cobbling together. Got above a 95th percentile score, but I doubt my study patterns would have worked well for anyone else. I did what makes me learn best.