And if your concerned with flavor, the two things are chamber volume and chamber volume.
I would have agreed with this until I got my Magma. My on the go PV is a Reo Grand with bottom fed atty's. The rm2 atty is a tiny little thing that has great flavor but the Magma is so good I have a modded bottom fed Magma on the way.
My Magma leaks only if I fill it beyond half way. My leakiest dripper is the Atomic; way more than the Magma. Single coil for me right around 1.2 ohm and 15W with most of my juices. The smallest air hole compares to a kayfun Light Plus for a super MTL. The 2mm hole is my choice for a lung hit.