I am looking at 3 possible solutions
Armstrong, DnD, and hermco.
Right now I am leaning toward DnD (
http://www.dadmarine.com).
You might want to look at DnD, they have a strong product for a good price with a lifetime warrantee (no I don't work for them). Most of these brackets look pretty much identical.
I think where you mount the bracket on the transom, and how you mount the motors has more to do with precieved performance, than differences in the the individual bracket.