My personal favourite is qtile and it’s been my main WM for a long time. I3 is another good option. Wayland experience looks to vary from the other comments, but if you do use qtile and wanted to try wayland, you can get it to run using it (although I’ve never tried it myself).
Linux Mint is definitely the right choice here in my opinion. I installed it for my parent's on their older laptop when they were having issues running windows. They were blown away by how fast it was and how they could do all of their usual tasks (i.e browsing, financing, basic games, etc.). It will be a great first experience for you!