For Conquest I'm loving Port Valdez, lots of unsuspecting vehicles that have to funnel through narrow places means that I get a lot of C4 kills.
Now I know this won't be a popular answer, but I love Atacama on Rush. I've pretty much got it down to a science now. I'm all over the place on defense, always with a damn good K/D(had a 22:0 run with a shotty just a couple days ago), and I can't remember the last time I lost the uav before the final set of M-Coms on attack.
Atacama Desert (conquest mode) and Panama Canal (conquest mode)