Oakleaf hits the important parts - the more powerful the better. The motor on mine is good, but not quite powerful enough so that what I actually get is extremely finely ground nuts that are almost butter - but it serves my purposes just fine. I like doing it this way so that I can choose the nuts and any other ingredients - but it isn't for everyone.

I hadn't noticed that Oakleaf. Do you have a local Trader Joes or Whole Foods? Both of them have most their nut butters in glass jars, at least around here.