From the perspective of United, I really want SEM to win. A semi final series with them is the biggest threat to United's title chances, as they could feasibly shoot the lights out twice in 3 games. Lots of weapons- Sykes, Gliddon, Adnam and Brokehoff can all either shoot the ball really well, or are just good scorers, or both. Then Creek does a bit of everything and Wetzell has a decent low post game.
From the perspective of a basketball fan, if United do in fact win their semi, a United vs SEM GF is a better proposition than United vs Perth. Based on recent results and the absence of Cotton, a United vs Perth GF wouldn't be great basketball. United has won 5 of the last 7 vs Perth including the last 3 in Perth, and several of those were comfortable wins. A healthy United would likely sweep, at worst 3-1, and Perth's best chance would be playing super scrappy basketball and hoping United throws it away. Not great to watch. Whereas SEM and United have had some cracking games this season, and SEM have proven they have the firepower to challenge United's defense.