I'm having a ton of fun with my AP powertech and I was wondering if there was a class that was as fun but made better use of DoTs.
If you want a class with the most dots, I'd go lethality/engineering hybrid sniper. It has 4 dots, Interrogation Probe, Corrosive Grenade, Corrosive Dart, and Orbital strike. The build is built around keeping up your poison dots (CD and CG) to make an ability called "cull" do awesome damage. IP should be kept up at all times too for additional damage. Orbital is more of a situational thing you use once a minute, but it is the hardest hitting ability in the game. If you love seeing rapid moderate numbers flash on your screen and a few huge numbers every now and then, I would suggest this spec.
Pyro in the PT tree also revolves around dots, but the rotation is kind of boring and repetitive