If Vape time is a priority, the LG HG2 or Samsung 30 Q are both 3000mAh and the highest capacity cells that would still be working near their rated amperage. You can get 3200-3500mAh Panasonics and LG but they're rated too low, at around 10A.
The HG2 and 30Q are usually more expensive than something like a HE2/4 or a 25R, so cost to life ratio isn't as good for the 3000mAh cell. I bought some HG2 originally for my Koopor Mini and while they lasted longer, I still had to use two if them to get me through a 12 hour work day, so I'd have been better off doing what I already was, and carrying a second HE4.
The more cells in a mod, the more attractive the 3000mAh cells are though. In a series mod that's an extra 1000mAh, and in something like the Reuleaux that's three lots of 500mAh extra, which adds up to something much more significant in terms of run time.