Make sure you get the alignment of the horizon correct...
I prefer to place on table cos of the flexibility when attaching cables or even shifting it around e.g old tv set to be moved to room and place new tv over, etc....
Make sure the brackets are universal so that new sets can be mounted too...dun wan next time your walls got so many holes..
Lastly, I prefer to look down from my sitting position then look up leh...more ergonomic imo. Better for postures and draw line of sight to your table. My 5 cents.