i would say stand off with mutli flag as that can be so much fun with my friends apart from the noobs that get in the warthogs. Valhala is also good on something like vip. i usually enjoy these due to me playing with my couzin and winning =-)
My favorite is Guardian it the best map for slayer Best i was a perfection in team slayer with 21 kill i felt great
My favorite CTF map is the pit, In team doubles it was 2 flag my teammate was not playing then they were up 2 to 0 then my teammate starting playing the we won it took us 3 min to cap 3 flag and the other team did not touch the flag the rest of the game and i got 10 doubles kill and a Triple kill in team Doubles
Tough choice but Im gonna pick Sandtrap for Big team Slayer just cause of the vehicles and the spartan lasers. I once got a killing frenzy and two triple kills in the first minute of play using only the spartan. Got the vid in my file share if ya dont believe me