I try to avoid 763's in C, if there is 744 or 777 service available to my destination. The C seats on 763's are noticeably narrower than C seats on 744's and 777's.

If I have to fly a 763 in C, then I prefer a window seat, preferably in row 5. Mostly because there is no one in front, which makes getting out easier since there is no headrest to limit movement and that folks walking down the aisles won't brush by, waking me from my slumber if I'm asleep.