If the pad is minimal, I'd go 0.3mm since you need to get in between the component and the pad to make contact with both.
Alternatively, go with a chisel tip that has a thickness of 0.3mm, but is actually wider than the component as long as the PCB isn't crowded the width isn't too important. As long as it's not crowded, the thickness of the tip matters more because if the pad is small, the component is too short, and the tip is too thick then the tip can't make contact with both pad and component because it gets blocked by the 90 degree corner formed between pad and component.
A guide:
**broken link removed**
Minimal pads are a PITA to solder though because it's easy to get the alignment off so one of the pads isn't touching at all, especially on smaller parts. If you're doing a lot of them go hot tweezers (or some would also recommend hot air).