What's everyones reasons for with the IMR chemistry cells being recommended? Best bet (IMO) is to go with a protected LiCo Panasonic cell (AW, Ampmax, Callies Kustoms, Nitecore, Eagletac, Fenix etc). Unless you're running high drain applications or want to be able to run the cell down to a low voltage without the protective circuit tripping (which will damage cells if done too low or regularly). Also bear in mind the cost of capacity (IIRC, highest capacity IMR is about 2200mah and LiCo is 3400mah)
Here's a good set of technical details on various cells. What torch are you planning to use them in? Have you got a decent charger?