I quite like isle if the teams are balanced, but cyclopean is great for adventures and lone wolf style of play.
I quite like cyclopean, but slaughtered has probably had the best games for me since 2.2, although I haven't played cyclopean much since 2.2 so I am mainly going out of slaughtered, canyon, and district, as that was more or less all the server played.
aww.. crossroad's not getting any love. It's my favorite since it's one of the only maps that doesn't require large teams to be balanced.
I don't like Xroads because there isn't any tactics to it. Votes duststorm for epic tank battles and CV chases.
Canyon and slaughtered because they are simple maps. No prop spam, no useless infantry tunnels, no complicated gameplay. We need more maps like that.