You want one that has opening in each end for the ridge pole to slide thru.Having the ridge pole on the inside lets you put up a hanger to hang wet stuff on,very important to be able to dry your stuff out plus warm dry boots in the morning. You want a good closure system at the door. I like a stove pipe port that goes out the side. It makes it easier to really poly- tarp the top well, when really hard weather rolls in. (Eliminates leaks too) Dirt flap around the bottom of the walls,(Cuts down on drafts) I have had several from 8x10's to 12x20's My favorite has turned out to be the 12x14 with 5 foot walls. My $ .02 ' Frank