When you're playing as a spy, even the most clever and quiet player will eventually get spotted and have to make a quick escape, or happen upon a merc and decide to press the attack. So which type of grenade do you drop first if you don't know what to expect? (obviously, people will not choose flahbangs when the merc is using motion tracking, nor use chaff while the merc is using normal, etc.) In other words, which of these do you usually carry standard and resort to first when you're surprised? Or do you not use grenades at all, preferring some other method to cover your escape/attack (for instance, a quick draw followed by a shot to the helmet)?
I usually use smokes all the way. Versatile, effective for both attack and defense, the smoke is probably the best grenade to deploy (IMO), both slowing and choking your adversaries, and providing a very effective visual screen.
Of course, if you can hit them with it, the flashbang offers much better visual concealment, and almost guarantees a neck snap if the spy is quick and vicious enough to dodge the berserk. I've never gotten the hang of flashbangs, especially since I'm almost never right in front of a merc when I get caught, and I'm never sure if I really blinded them.
The chaff is good to throw in dark areas in order to stop the MT and EM visions, but mostly it's handy to make short work of security, especially the lasers in aquarius. I loved the chaff in PT, but I find it pretty useless overall in CT, so I carry a heartbeat detector instead.
I almost never shoot mercs with shockers. What's the point? It makes them invincible for a few seconds, pisses them off, and probably gives away your location. A definite last resort.
Post your choices and explanations here, and show your ub3r l33t strats to the rest of us.