In regular rotation, probably about 6 tanks.
My favorites are the Fogger V2, Kayfun 3.1 (clone), IBTanked 22mm XL tank, and the Aspire Nautilus.
I still keep my Kanger Protank 2's in rotation, I've sorta put my ViviNova tanks on the back burner for a while, and have about eight different dripping atomizers that I usually only use at home and mess around with different wick and coil setups.