Well, all things considered...
If you find two PSU with near identical specs, with the exception of one having PFC and the other not, You'd be better off getting the one with PFC (active PFC is the best). It may not be a critical aspect as to powering your rig but, it's always better to have it than to not have it. Besides, when comparing like PSUs, the ones with PFC produce less heat and, therefore, contribute less heat to the overall system heat.
As I said, though, not everyone really places alot of importance on PFC so it's personal preferance.
As for 12v rails...
With the exception of PC P&C and Athena, most reputable brands tend to have more rails the higher in wattage you go. However, don't just pay attention to watts or rails or PFC. Amps are every bit as important as any other spec.
Take my Silverstone 750 that is powering the rig I am on now - Active PFC, quad 12v rails, 18amps per rail.