one thing I really like about tf2 is atmosphere...they have some great map design. My complaint with CTF maps from the beginning was how boring they could be - how it used to be: "take some single player space, map out special items, mirror it for the other team, done." A perfectly symmetrical and boring map.
TF2 maps have similar route spaces, but enough detail tweak to give the appearance of asymmetry. Plus the attention given to surrounding space outside the playable map areas is pretty good.