Personally I find deathmatch, or team deathmatch only worthwhile as knock-about and to perhaps warm-up the reflexes before a game.
HQ is good fun, however you do need a team that understands what needs to be done, sometimes it appears your just might as well be playing tdm tho. Though when you get two teams thats know what needs to be done its great.
Also the rifle only servers (Germans vs Brits) I find are a good laugh, however I did have a propensity to use the rail in q3, and I did like instagib, so perhaps thats where my infatuation comes from