I do both depending on which device I am using. With my Halo G6 and E-Fire with protank 3 mini, I do mouth to lung hits because of the tighter draw. With my hammer clone mod with aerotank mega, I do straight lung hits because it feels more natural to do it that way with that device. I cycle through all three devices all day, depending on circumstances. I use the G6 cig-a-like while driving and always stays in my shirt pocket as a backup device. I use my E-fire and Hammer clone on breaks at work and when at home. Each of my devices, I keep with a different flavor to keep it interesting.
At home, my little charging table does get quite crowded with all my e-cig batteries, cell phone, and bluetooth headset charging at night.