A Mech is unregulated so no VV, VW included for what that is worth to you.
But a mech is not limited to how low in resistance you can make your coil, given you know safety guideliines and ohms law.
A good standard for a mech imo is conductivity = less voltage drop = better performance.
Metal choices are important imo... for conductivity get either brass or copper (highest but most tarnishing).
Next standard is cap options; top and bottom switch; designs are important in regard to ease of use, setup and adjustibility.
imo the Brass Nemesis is a winner (either real or clone; they perform the same; copper clone is great too)... but along with conductivity, the bottom button design is genius; no need to fiddle with top cap for adjusting for battery rattle (oooh i hate adjusting for that). Just set your atomizer, insert battery and snug the bottom cap and go... and go... and go.