PineCone as some of the members call it is the most difficult for me. The more holes I play the higher the CPU meter goes as the VEM is cranked to unbelievable levels.
Having played Valhalla many times I look forward to seeing how WGT can screw that one up if they ever decide to release it.
Oakmont is love and hate for me as is Merion, some really good rounds on both and some I would like to forget.
Any course other than another Par 3 course would be good, those are a waste of time and money imo.