I don't like my Top Swings, mud and stones around here collect in it rending it useless. Quite a few times in the slight muddy conditions where stones and things can get picked up it's had granny gear rendered unusable as they get under the pivots and jam it.
(acts as a stop)
They have a tidier cable route for top pull setup though.
You may be dictated by the frame tubing (and flaring/ovalising at the bottom stop use of top swing or bottle boss position can stop use of bottom swing.
I prefer the look of bottom swing.