I'd have to recommend against the P220 for competition. It has a high bore axis, which means more muzzle flip. The DA trigger is also something that can be hard to get used to, especially on many SIGs where the DA pull seems God-awful heavy. Then you're limited to single-stack magazines.
It's an awesome service gun, but it's difficult to be competitive with it when everyone else is shooting low-recoiling 9mm's.
I shoot a couple of XD's myself, in .40. I load them light for IDPA, put in a lighter recoil spring and they shoot like a 9mm. If you want to be different, the XD's are a good choice, as is the CZ-75.
If you can stand the Glocks they would be a good choice. Their low bore axis, high capacity mags and consistent trigger are the selling points. I just hate the position I have to contort my hand into to keep from rubbing something raw or getting pinched. I have a couple of Glocks for range use but I'd hate to shoot them as much as I do my XD's. But if you don't have a problem with them, you'll probably do well with one. The top IDPA shooters in my area generally use the 1911, FWIW.