A draw is the worst option. I'd rather Saints win, personally.
If West Coast wins, they still have to win two games from Carlton, GWS, and Adelaide to mathematically prevent Hawthorn from jumping them. If they lose, then they'd need to win all three.
If St Kilda wins, they have games against Melbourne, North, and Richmond. These games are much more winnable, but they would need to win all of them to 100% ensure they finish above the Hawks. If they lose, then they rely on Hawthorn dropping a game to ensure finishing above them.
A draw would basically be a win for both of them given our percentage. West Coast would need to lose 2 of their last 3 games for Hawks to possibly jump them, and the Saints would need to win all their games (and maintain percentage) to stay ahead.
A Saints win means that WCE and the Saints would need to win all their games to prevent any chance of the Hawks jumping them. Both teams would be playing two top 8 sides, with WCE playing two top 4 sides. And if the Saints win all their games, that means they have to beat Melbourne, which leaves the Dees vulnerable to being jumped.
A WCE win takes the Saints out of the equation assuming 4-0, and now WCE would only need to beat Carlton at home and one of GWS away and Adelaide at home to ensure finishing above the Hawks. Still tricky for them though.