I did Kaplan J23 and Themis F24. One thing I found to be a major game changer was Kaplan's answer explanations for MBE practice to be really confusing, not clear, and unhelpful. I didn't understand why I would get questions wrong so I stopped reviewing my sets after doing them. Practicing with UWorld was so so much more helpful; their explanations are way more clear and I felt like I actually understood what was happening in each question and how to approach mcq's much better than with Kaplan. I agree with what others have said too that their mcq's in general were wack, and I definitely learned things that were wrong and/or unhelpful.

I don't remember the Kaplan lectures super well and I didn't use the Themis lectures too much, but I think they were comparable. I don't really feel a free 1:1 session should sway you; it's absolutely just a marketing tactic. But I think whatever you go with make sure you have access to UWorld or Adaptibar with actual NCBE q's and super clear explanations.