Well, for all of the above, ATH/SPD/DEF for starters. With Speed first for guards, ath first for posts, and roughly equal with neither low for Small forwards. Then add in BH and Passing for your guards, and REB and BLK for Posts, then worry about PER and LP, more PER for guards, more LP for posts, SF< whatever it is you are short on. Generally you probably want at least two players between your two guards and SF which have a respectable PER and two players between your two Posts and SF that have a respectable LP.
Basiically, I often tend to treat the SF as the spot to insert whatever else the rest of the starting lineup is lacking.