assuming the hearing aids are equal ...
I think the BAHA looks better (Im bais of course) .. nothing in your ear, no ear wax, and if you have hair .. most of time you can't see the BAHA)
Bad things are, you can't wear a HAT! .. but for me, in the office I never have a hat and when I'm out working in the yard or fishing, I dont want the BAHA in anyway! so a hat is ok. Longer wear times .. your skin does not have feel the aid vibrating, so wearing it 16 hours a day , I dont have problems ...
I assume with a Trans ear you can wear a hat ... you dont have a bolt in your head ..(who said I have a screw loose!) no surgery required .. no bald spot .... I would say the older you are the better Transear looks .. but you have a big Hearing Aid in your ear .. Its harder to hide .. (should make them look like bluetooth). Some people can't wear them because of ear canal issues .. etc...
The BAHA was made for "Treacher Collins" .. people born with facial issues , little or no outer ears or eardrums. but the INNER ear is perfect ... in these cases the BAHA is the ONLY choice and works wonders ... I watched a TV special on it not to long ago, and a young girl they interviewed had a BAHA on! (they did not say much about it)
check out:
http://www.baha-users-support.com/cgi-bin/2bb/2bb.cgi or
http://www.transear.com/