Which of these 3 lights should I get next?

I have a Th-T60 and use it as the light that is always hung just inside my garage door. A little more focused throw (larger head) than a standard P60, but not as focused as the even larger-head on the C8. So it depends what you want. The Th-t60 fits into your pocket easier than the C8, but will give you a less-focused hotspot that is wider.

Can't speak for the X9, haven't gotten one of those yet.

You can see some beamshots of the Th-T60 here, as well as the Trustfire F15, which has the same head and emitter as the C8