i fly the dash-8's a lot and if you cant get the exit row (the OP obviously wouldnt be able to) then the last row middle seat is the best if the flight is full. if you're traveling with a bunch of people the last row is also good.

if it isnt full then i would honestly say that any seat is fine bc the seats dont recline anyways so your space is "protected" and the 8's are generally less cramped than other express aircraft. find a row without anyone else in it and you'll be just fine.

it does get loud but it really isnt so bad. its actually a nice change from the monotony of the noise jets produce