Just wanted to get an understanding on what flying mode is primarily used.

I use atti more especially when doing videos. You get much smoother video in atti mode.

For sure, ATTI is the way to go if you're looking for the best video. Probably 90% of the time I'm in ATTI and I basically use GPS mode to position hold if I'm doing a panoramic shot or if I'm waiting for a subject to get into position.

Couldn't agree more Simple Panda :-)