The eGo is the benchmark, but it does seem like things have changed quite a bit in the last year... check-out e-cigarette-forum.com for a community as nice as CPF (they call it ECF, which makes it sound familiar to us CPFers). Right now I'm vaping with the EV Torch tank system:
http://www.electrovapors.com/shop/index.php?route=product/product&product_id=355. It's based on the eGo system standards and..... DRUMROLL!!!!!!! ... it also can be used as a flashlight when in lock-out mode! I didn't get it just because of the flashlight part, but mostly because of the reviews and the fact that is is a Canadian product (still mot likely made in China, though). I am thinking about getting something more recent as a next e-cig however...
I've had this one since November 2012 with only 2-3 tank leak problems in all that time, once of which I suspect killed one of my batteries early on. I bought 2 bigger batteries, but haven't tried the variable voltage adapter yet, but I understand variable voltage is a must try, though. A lot of the newer system use an 18650 battery for a power source!