Beck I agree with Daisy on the herbs, they are pretty hardy and I only give mine a bit of cow manure in spring and that's about it.

Some plants, like mint for instance, are better in pots than in the ground. Not because they're happier there, but because if they're not contained, they have weed potential! You need to keep repotting and cutting the roots back to size with plants like that. I keep fennel in a pot because of its reputation for being an 'enemy' to other plants grown nearby, and also because it self-seeds madly, and I want to control it. Many of my potted plants are those which like more shade than sun, which is an important consideration in my part of the world where the sun can be fierce.

Then there's the aesthetic appeal of pots (or rather, the lack of it!). Although I have many potted herbs, it's mainly because I have a tiny garden area (my entire back yard of plantatable area is not much larger than your average lounge room) and there simply isn't the space to plant things out and to let them get big and beautiful. And they look untidy and unnatural, to me. Plants in a garden bed always look so much happier and prettier.