Mostly I use panniers; but I have a large collection of backpacks as well. My top end is an LBB

If you need to haul a lot of stuff on your back, it's a solid choice.

The Arkel backpack pannier is good (much smaller), I have a very ancient model and it works well.

Mostly you need to figure out what works for you. It may be a family of bags, for different loads ... or you may find one you just love ;>