This is the first synth I've really worked with that's able to do FM since Sytrus in FL (I don't do much FM in Thor). If you're an FL user like I used to be, you know that FMing a saw wave is pretty much the worst thing you can do. So, I was surprised when I FMed a saw by a square in SubTractor and it didn't sound like trash. While you can do more with Thor, I still prefer SubTractor for FM (at least until I get PX7). It's also good for sub basses and simple lead sounds.