Very nice tree and work.
I like to go "native" with quirky trees like this one and avoid the typical Japanese/tokoname pots. They're always a fall back, but native potters can give a tree like this one an extra visual bump, IMO. They also-- depending on what you're after--might be a little less expensive.
For such a rugged looking trunk, I'd consider a rounded square with some rugged accents, like rivets. Sara Rayner's pots manage to combine some refinement with ruggedness. Her "rounded square" pot with rivets might work with this tree:
http://www.redwing.net/~daalms/rectangle.html
Glaze could be the dark slip in the pic, but you might also consider a green/grey glaze too. Her "Green ash" or "blue green ash" might lighten it up just a bit.
http://www.redwing.net/~daalms/glazes.html
You could also go a little lighter in the pot's visual weight, with a shallower oval, or shallow rectangle too.
Ron Lang makes a pretty mean heavy oval that might work.
http://www.langbonsai.com/oval.htm
His "peachy satin with salt influence" glaze would work here, as would the "frog" glaze:
http://www.langbonsai.com/glazes.htm
Dale Cochoy has many distinctive shapes and glazes that would work with this tree too. His pots vary greatly, so you'd have to check with him about the particulars.
