Mixed AB is your best bet until 70. It's hard to get queues for AV until 70 or so, or at least it was for me. Then most battlegroups will have at least 2 running during normal play hours (8AM-Midnite server) I really wish I knew how to make a GOOD mesh in AV, the stock one seems to wander a lot, or make a CC that follows the zerg rushers or tries to cap flags in EOTS. But alas, I am terrible at coding.