i have 2 SFs, for inside and outside purposes
if you want just one, then i suggest high OD, and reasonable ID, good reb (7+), reasonable DV and passing (6+)
shooting is also important
now you see why i have 2
having your SF to be a good inside and outside player is tough
i somewhat prefer outside skills on inside ones for SF, but you can't have a too weak rebounder or defender in that spot
if you go for inside SF, driving is quite important