Literally any computer will do. As a general rule of thumb, you might have compatibility issues if you use the very latest chips as they were not well tested with Linux yet but I also think that's less and less of an issue. 

 Linux runs on a bllion devices. Anything really. Whatever you have now is probably fine? You can buy pre-built systems with Linux if you'd like to do that as well. System 76 is popular. Frame.work is a new and sex product line as well.