Self watering pots require specific media. Google 'hempy bucket'.

Potting mix is usually peat, lime, and perlite. Sometimes it has fertilizer added to it.
Potting soil has true soil added to it as well, but is often also peat based.

Any mix that you understand how to work with is the best one. I don't like self-watering systems unless they are true hydroponics, in a hydroponic mix that is designed to be watered automatically. Sure, commercial growers run promix on auto watering pretty frequently, but a noob should hand-water and learn the plant because over-watering is REALLY easy to do.