champion plugs
I've tried most brands of plugs and never have detected a difference in how the engine runs. I do use platimum plugs in my daily drivers just because you don't have to change them as often but they certainly don't make the engine run any better. I use conventional plugs in my toys just because I like to fiddle with them and it makes me feel better.
I most often purchase Autolite brand simply because there is a Wal-Mart near the house and they sell them and Champions next because everyone else always has them.