Are you coming out from Glasgow? If so, the availability of the train line via West Calder might make your decision for you, as it turns into a replacement bus service in the evenings at the weekend?
If that weren't a factor, I'd suggested Livingston South regardless, as there's a pretty regular (every 15-20 minutes) bus that goes from South to the Bus Station (Centre). Not sure how much it is these days, as I tend to drive if I'm going to Livingston for anything.