If you want a learning management system that you can depend on, then LearnDash is the best choice between these two. I have serious reservations and concerns with LearnPress, the quality of their code and the support you would receive when issues happen. While I don't think the support process with LearnDash is that great, ultimately you would receive better support there. There is a reason universities trust LearnDash, because they can't afford for there to be a problem. The pricing from LearnPress is better, but it's just too good to be true.