Best can mean so many things... Best bulb or best lighting system? Best color temp (again, a relative thing)? Best cost per system? Best cost per replacement? Best operating cost?
If you're looking for something more broad or nondescript, I'd say LED lighting, whether it be the Aquarium LED, a custom system, or DIY. LEDs might cost more up front, but a quality LED setup will cost less in the long run (chilling and electricity usage) and they're just cool.
If you're not sold on LEDs, I'd say T5s. They have great intensity, enough for SPS, but don't pump out as much heat or use as much electricity as MH.
To each his own though, and these are just the solutions that I like or are attractive to my reef-keeping goals. Results may vary.