eGo batteries last and are 510 threaded. There are lots of options with the eGo from using 510 attys and cartos to tank attys, mega attys, and eGo specific cartos.
The go-go system seems to be getting popular. It is a carto system with a big battery.
There are many wonderful mods to be found from
juice feeders to MAP
tanks. The REO bottom feeder has a big following along with Alii and a couple of other bottom feeder makers. There's also high voltage or variable voltage to think about now.
You might need to be a little more specific about your needs than just lots of vapor and good battery life. Technology hasn't just gotten better, it has gotten more diverse.