Yea python or krait for a medium ship but a conda can carry so much more and even with mining tools in the loadout it will still have the ability to decently defend itself in a fight so go for it if you can afford it. its what i use
For medium ships you want the Python because it has one more optional internal (lv6) so you can carry more stuff. The Krait MK2 works as well but if you want maximum reward you want the Python. For a large ship, the Anaconda and Corvette can hold somewhere between 300-400, but if you want to go all out you can get the Cutter which can hold 640. I’ve used all of these ships and I would say the best is Conda or Corvette because they can hold a lot but not so much you’ll be mining for days.