I doubt 250 pounds would be much of a problem for any of the high end bikes, but you'll want a high spoke count or smaller wheels. Bike Friday is custom, and thus the best for your size. Birdy will need a green elastomer, and you'd be best off with the monocoque frame (in the US, it comes with a silly spoke count--the 36 spoke wheel amounts to something like 72 spokes on a full size wheel).

Happy riding!!