I like the Prof Bodkins a lot, easy to get on/off and roomy. The freezable water pack is nice too. The new SW version has no zippers to rust.
I haven't been shopping lately but I like a chest pack that has a removable rear compartment large enough for water bottles, snacks, extra spool, 2nd flybox, etc.
The compartments have to be big enough to hold the large foam Morrel (?) flyboxes on both sides for me.
Ideally, the rear compartment would be a waterproof one like the SEALINE bags and packs. This would allow cell phones and other emergency items to be safe in case you get soaked. A simple fold and clip top would do it.
I like my chestpack but the zippers handles rotted off. I replaced them with brass split rings and they are holding up so far. I guess it would be a good idea to rinse them with my other gear, never did that.
I am sure others will chime in...