Resurrecting an old thread here but one that's been on my mind.
I use a Patagonia Stealth Atom sling bag to carry all my gear. In the sling bag:
I'm also wearing or carrying a ball cap, polarized sunglasses, cell phone, waders, wading boots, and rod(s).
The sling bag is fairly small but contains all the accessories I need; I grab it and my Simms Taco bag that holds my waders, boots and rod case, and I'm good to hit the water.
I've tried a chest/backpack combo but one big downside is you can't wear it around town without looking odd. The sling bag doesn't have that problem. If I don't need waders or wading boots, I ditch the taco bag and it's just the sling and a rod.