CP_5gorge- TF2
I always liked the original, but the second point always became a stalemate. 5gorge fixed this and i'll jump on any server playing the map.
Facing worlds- UT series
Everyone knows where the redeemer sawns, ample sniping opportunities, open ground with the key powerups in risky locations, constant risk of falling off the edge and yet very easy to capture the flag: it truly is a great map.
Necropolis- UT3
A VCTF map where a foot soldier can easily dominate those in vehicles. Great defensive opportunites while still allowing for a quick and stealthy flag capture.
Snow blind- 007 Nightfire
A couple of useful places for the grappel, lots of passageways and shortcuts as well as use of height in otherwise narrow corridors.
CTF_doublecross- TF2
Probably the best CTF map in TF2 and a great place for learning any ambush class well. It also tests any engineer and has great spots for pretty much any class.