I keep two packs ready at all times, an Umpqua Overlook chest pack w/back pack for most of my trout fishing on foot, and then a Fishpond Waterdance Guide Pack, which is a lumbar pack with a shoulder strap, that I bring along and strap to my seat in the kayak, or I'll wear it when I'm wade fishing for smallmouth and carp locally as I don't need to bring as much stuff.
I like the Umpqua the best out of the two, as I'll often need to wade deeper, walk further and therefore carry more stuff, and that backpack is a huge help. I'll throw a couple bottles of water, some TP, and my streamer box in the back pack, then keep nymphs/dries and all the terminal stuff in the front part. I do love the Fishpond bag too, but it gets swamped often being around my waist rather than up on my chest. Also, I had one zipper issue with the fishpond, and they sent me a brand new bag no questions asked. I also LOVE the net holster on the fishpond. You have to use a magnet system with the Umpqua to carry a net.
Were I to buy a new pack, I believe I'd try one of the new Fishpond Cross Current or Thunderhead chest packs, which have the utility of the Umpqua with the nice net holster on the back. But not sure if they have a back pack option.