C&R, ...
As you see, ... we answer questions with questions ...
$$$ ? You can get some pretty pricey vests out there.
If you drag around LOTS of stuff, ... (4 boxes of flies), ... do you need a BIG vest. Lots of pockets for lunch, rain gear, coffee, extra spools??
You can look into vest and packs.
I prefer a vest as it has MORE pockets for little stuff. I also drag around a kit bag and drop it on the beach. I have about a dozen fly boxes on some runs, so I keep 2-3 on me and the rest stays on the beach or in the canoe with the jackets, snacks, drinks, dawg etc.
Pricey vests from Simms, Pantagonia etc are nice. Make sure to bring you biggest fly boxes with you when you go shopping to make sure they fit into the proper pockets.
I took a while to find on. Zippers have to go the right way, on the proper side etc.
Mine has 16 pockets plus tippet slots on the inside for spools. 2 upper back pockets for extra spools. Built in retractors are nice, .. but not essential, as you can buy reasonable ones at Wally world.
My girlfriend has one which the back can zipper off to make a mesh back vest in arm weather. Personaly, ... I still haven't found full mesh vest that hangs right on me.
Take your time looking, ... vests are hard to fit and you'll have it for years and years.
Look for quality zippers, stitching and hardware.