I find skewb to be very unintriguing and kinda lame. Pyraminx is fun if you want to challenge yourself by learning a puzzle intuitively, making your own algorithms, etc. because it's a relatively simple puzzle. You will get fast quickly and th that's just kinda all there is to it, there are advanced methods and all sets but nothing like what's available to explore with 4x4. The 4x4 will require the most time to master of the choices and is arguably the more difficult, expansive, and fun of the options.