Huh? I mean, HUH? What sort of snowpack are you placing your pickets in? Gleaming blue snowpack?
Proud owner of a couple of those Yateses
It doesn't matter one bit what type you get, so just pick the prettiest colors. Mine are orange! They brighten up the gear collection quite a bit, especially since they never leave the house.
If you really have to be anal about it, the T shape is classic and does the job, the L shape has a packing benefit and packs the snow diagonally outwards which supposedly helps (but your buddies will place the picket backwards so nevermind), and the guards on the top of the picket actually make it live longer but only if you're hung up on not tearing apart the rest of the gear. Oh, and did I mention the pretty colors? Cost more though...