Absolutely without a doubt #1 EVER and has been for YEARS:
#1. Blue Cheese!!!!!!! (I even mark my jars with the exclamation marks because I'm excited about it) the roaches from Blue Cheese go in their OWN Jar so when I run out I have those to smoke some. I DO now keep jars or bags set aside for other strains too, like Motor Breath and Chem D and so on, but Blue Cheese is generally separated from the rest and I rarely roll up any of it with something else into a house blend LOL.
#2......... Now it's going to get convoluted :
#2 and #3 and so on are a toss up.... Chem D, Chemdog, UK Cheese, OG Kush, Purple Chemdog, Blue Dream, Green Crack, Skywalker, GMO (A recent addition now that I finally tried it).... I imagine I'd LOVE Blueberry but I've never had it. Had lots of it's kids though LOL. MSG is up there too.
In terms of making my top list, Smell and Taste play a part in it, but not as much of a part as the effects; Blue Cheese I generally wait until the Resin is getting a little Amber color to some of it before I pull it, because I like CBN to be in there too.