A mouse is much heavier than a tablet pen and is also easier to grip. I feel quite comfortable with a mouse up until this point, but it seems that using a tablet is "more common". It really depends on how you feel with the grip of your peripheral. You can even fine-tune your control with areas for tablet pens or DPI for mouse. I personally have always used a mouse, I started with an office mouse with a fixed DPI and high sensitivity on osu! because I had little space. I now have a mouse with a DPI setting that can be changed, but I'm so used to my old setup that I use a pretty high DPI now. Either way, you will need to feel both mouse and tablet pen for yourself and experiment before you feel comfortable. One thing is for certain, try to avoid Bluetooth peripherals as those can provide noticeable latency.