I went through several phases. Just a couple of weeks ago I used the vest for the first time and I LOVE it. I still think that you need more than one thing depending on what you do.
I started with a compartmentalized back pack
http://tinyurl.com/d2xl7n. For me, that was over kill because I did not have that many things to carry in it. I still think that it is good if you have a lot of gear and also to move stuff while you are not shooting (like at the airport). One story of caution though. Once I was walking along a very crowded “magnificent mile” in Chicago with this bag on my back. Some asshole that I did not see actually opened the zipper (you can see in the link it opens entirely like a clam) and a bunch of stuff spelled in the middle of the street (I was crossing on top of it). Thank God I had the camera on my neck and not in the bag and I had very few items there and a lens with a protective bag. It was unsettling but thank God no damage happened. After that I started tying the ends of the zipper together.
Since that was over kill for me, I moved to a waist bag that has two lens compartments on each side. This was a great improvement for the few things I want to carry around. Very easy to get to the camera and if you are walking you can slide the bag to rest on you back. In the time being I only carry a telephoto zoom in addition to the lens on the camera so that leaves the other lens compartment open for a future lenses. A separate pocket that goes on the same belt (on the other side) is big enough to carry extra flash cards and batteries. There is also a side pocket on the camera bag that is big enough for flash and a small lens and cleaning tools. The bag has also two straps at the bottom that allow me to carry a small tripod or a monopod horizontally.
Lastly, in my last trip to LA, I tried the vest on some of the walks and I thought it was great too, If you don’t have a lot of gear. I was able to carry everything that I carried in the waist bag in the vest, except for the tripod which I either had to leave in the car or carry with my hand. I did not go for the most expensive vest but I got a very reasonably priced one off of Amazon and it was great.
I think I will still use all of the above on different occasions depending on the need. The least will probably be the back pack.
I hope this helps you in your quest.