For fishing …
I started carrying a WillyJ exodus pack this year and am really liking it. It allows me to carry a bunch of ‘stuff’, but it rides really nice. 😉
If I am going to hike and want to take more lens options .. I switch over to the Burton Zoom pack and reduce the ‘extra stuff’ factor a little.
Usually: Camera + 1 extra lens, small(er) net to screen for bugs, fly box(s), backup hat, shell, misc small bag (license, headlamp, allergy pills, sun screen, gum), small lomo film camera, katadyn water bottle, extra tippet, sinking line spool, floatant, flask, lunch, and a ghost net.