I refuse to play any non-hardcore server. If I shoot someone in the chest a couple times with an M-16, they had BETTER die! I hate the killcams, because they're gamey, and I find regular invites the horrible spray-and-pray n00bs that have prevented me from playing any other online FPS. Hardcore results in the perfect balance between all kits I find. Too many of one type and you will lose, and all specialties have strong weakness and advantages that you DO encounter in every match.
If anyone is looking for an AH-like environment, I'm in a clan that is mostly 30+ retired military folks. We play for fun, none of the childish stuff, and operate 4-5 of our own dedicated servers. If you're interested in joining up, or just hanging out, PM me for server and Teamspeak info.