Oregano would be what I would suggest, it grows quite easy and it is a herb that you will use. Just about any mint is fine, they are pretty close to indestructible. If you have a cat try a small pot of catnip. Just don't let kitty eat it all at once. I find the two hardest to grow are rosemary and thyme. They like it cooler and they are sensitive, My outside rosemary did great this year, I had quite a bit which is unusual. Whatever you do, if you go for mint do not put it in the ground, you will have that stuff everywhere before you know it. Made that mistake with lemon mint. Wow it replicated as far out as the front of the house.