I own a Screwdriver, Zi-Moshi, 510, 901, 801 penstyle, and 2 of the v1 Janty Stick.
The JS is #1 for me hands down. I have not experienced the issues with v1 that others have. With a built in passthrough and a battery that lasts 5 hours with heavy use (and cheap to replace too) it really is my primary ( and virtually only) vape. Janty stands behind their product, so if there are any issues, they will be resolved.
I already have v2 on order for shipment on 7/7.
I don't mean to sound like a total fanboy, but I have invested almost $3,000 in my total ecig experience, and for my money the Janty Stick is #1 so far.(That being said, my wife would probably get rid of me before she'd get rid of her 510, so the 510 is a great choice as well)