My top 3 are currently:
Massive: I'm still a synthesis noob, but I've finally started to grasp this subtractive synthesizer. It does everything I need and more (beyond your typical mid range wobbles). Going to be my main synth until I sack up and learn FM synthesis

Gross Beat/Dblue Glitch: Been using Gross beat basically since I started using FL9. Its simple yet effective at gating and time stretching, etc. I've been getting into using Dblue more lately because its much more capable than gross beat.
Battery: Sooooo many different drum sounds/kits

SliceX is a close runner-up.