What is better?
I'm reading the loomis books on figure drawing and should I practice with pencil and paper or draw on a tablet?
Tablet is just an art toolm anon. You can technically use anything you want as long as you can practice your fundamentals.
Many people here will suggest using pencils in order for you get those good values out. Some will recommend pen in order for you to control yourself not to do chicken scratch strokes and keeps you aware of your mistakes at is not erasable.
Either way, your choice.