You could also check out the mega attys. They produce a ton of vapor too. - That's the really cool thing about the ego. It's very versatile. The batteries are really quite good and 510 threaded, so you have a ton of choices on how you want to vape. - I have both styles of megas, regular tanks, LR tanks, and a plethora of 510 attys. There are also ego specific cartomizers (never tried them personally).
I like my tanks quite a bit (very much so for my sweet juices) but I prefer warmer vapor for my tobacco flavors, so I usually bring a mega atty and full cart with me to work - or sometimes a 510 atty and a little bottle of juice if I plan on having free enough hands to drip. I mostly use my tank, but it just takes a second to spin it off and spin on something else.