I'm going to assume the top of everyone's list is safety, reliability and quality/build. That aside, I think a lot of it depends on what the buyers primary use is going to be and whether or not they have water front property or trailer it every use. My 2 cents...
Average "waterski" family who lives on the water:
1. interior/exterior functionality (seat layout, platform, helm)
2. wake (combo, slalom, kneeboard, trick, beginner wakeboard, tube :s )
3. speed control (something that keeps you close, but not worried about world records)
Average "waterski" family who doesn't live on the water and trailers their boat:
1. storage
2. interior/exterior functionality (seat layout, platform, helm)
3. bimini (sun management)
I'm just guessing people buying an outboard boat are not slalom course buoy chasers, 5,000+ point trickers, surfers, or extreme wakeboarders.