First thing first: have your fit measured both for lenght and width. Buy your softboot in Mondo size like you'd do with your hardboot.
Second: go to a shop and try all the boots brands. Not one company fits alike. I have a K2 foot, no point trying to fit into a driver X or anything else. The only thing holding my feet properly is K2. So find the brand your foot is the most secured in and get the stiffest boot they got.
If you have wide feet your choices are limited. So far, I know of the Maysis Wide, burton ruler wide and burton photon I believe.
Try them all. Do not shop for a perticular model.