At least in the ATL area the PCA does much better auto-x events in my opinion.
Plus in the SCCA there are a lot of cheesy bling bling cars wasting daylight out there... Meaning less laps for you. Also the SCCA starts are from a standstill and could possibly be hard on the clutch, in the PCA you get a rolling start in 1st. Granted the SCCA big power cars have some sweet burnouts
Not to bash the SCCA as some of the drivers there are ungodly good.