My GGT is now 1 week old and I haven't used any of my other big batts since I got it, except for at work where I've been using using my 501 in its standard form.
My 3 favorite juices in the GGT at 3.7 volts (Nano) are Apricot Brandy w/a hint of menthol, English Toffee flavored Ecopure Rich & Cotton Candy (24-36mg). At 6 volts, I'm a sucker for Caramel Apple and Thin Mint (18-24mg).
I have loads of store bought flavors but I also DIY and tend to switch between 3-4 different flavors daily. I'm really excited about getting the AFS although it will limit me to 2 flavors a day since my daily intake is about 2ml of juice.