Cat5e or Cat6. Both will be adequate for cameras, and both will carry PoE (power-over-ethernet).
Might also want Coax cable for video distribution, or regular cable (terminate it in a large wiring can in a closet somewhere, where a video distribution system (or splitter for your home cable) can be placed.
Terminate your Cat6 in the same closet/can.
Make sure there is power run to that closet (eg. an electrical outlet or two... those often aren't put in closets... even better to put an outlet in the bottom/inside of your wiring can). Also make sure there is ventilation: an AC duct, or exhaust-fan to exhaust warm air into the attic. With the latter, you can plane an inch or two off the bottom of the door to allow cool air into the closet, while the warm air is exhausted out the closet ceiling.