I never said I could beat you.
A low serve works pretty well, unless that is the only serve you can hit. Then the opponent just lowers his backswing and deals with it like a feed ball to start a rally.
Personally, I like the idea of having a twist that goes around 5'10" at the baseline, a flat that hits maybe mid tummy, a top/slice that goes mid chest, and a pure slice that slides past around upper thigh heights.
I could use a lower backspin slice, but then I could use a reverse serve and a 150 heater, but those won't come in my lifetime.