I’m not exactly an expert, as I’ve only used 3 or 4 cubes, but I would definitely recommend either a dayan guhong, or a dayan zhanchi. They can both cut corner amazingly well, and turn effortlessly. I personally like the feel of my guhong better, but the current world record is held using the zhanchi.
I love the shengen F2, it’s what I use. Dyan ZhanChi is good as well. The Dyan GuHong is just as good. I honestly recommend starting with the F2. MAKE SURE YOU TIGHTEN THE SCREWS. All I can tell you, unless you want it popping constantly.
I can solve 2x3x3, 2x2x2, 2x2x2 and 4x4x4…I’m working on 5x5x5 now. I’m kinda slow on all of them, but I don’t do it for speed…I like the journey. I have two 11x11x11s in my collection, but I probably will not learn those for a long time from now. I have some cool stuff in the collection. My favorites are my metal 3x3x3, real heavy, and my wooden Rubik’s that turns really well after lubing. If anyone wants an Edison 3x3 cube, I have them and can sell you one real cheap!!