What's your favorite flash game, and why?

Mine's Burrito Bison Revenge. :)

Happy Wheels... I still play it very occasionally. It's simple, kinda fun, and stupidly violent.

Was Heavy Weapon initially a flash game which then was ported to consoles? If so then I would say that one. Played it on the Xbox 360 and loved it.

I used to play a lot of slime volleyball and that helicopter game on ebaum's world way back in the day.

Outside of hentai games,

Fear Unlimited 1 and 2.

That game where it's like wave based zombies and you're behind a wall and you buy upgrades.

Pico games on newgrounds

A few dating sims

and yeah, other stuff I guess.