For trail running, I use the Salomon Advanced Skin 5 for nearly all my longer runs. I also have the Salomon Advanced Skin 12. I use the 12 for all day, self supported trail runs in the mountains. I use them both the same, just carry more stuff in the 12. I'll carry up to 4 full soft flask water bottles, a filter, rain jacket, extra layers, food, etc. in either. My 5 has one zippered pocket on the front, the 12 has two for whatever you don't want to lose. For the most part, the all pockets are all pretty accessible without taking the pack off. They both ride really well with virtually no bounce. There are also bungees on the outside to strap down additional layers or trekking poles.
I also have an Innov-8 pack with a removable pouch. It's a decent vest, but it pretty much just hangs in the garage in favor of the either of the Salomon packs. I've also run a bunch of miles and races with an Ultimate Direction vest. It was a decent vest. But it got perma funk, so I started shopping for something new. That's when I got the Salomon AS 5.
You won't go wrong with the Salomon vest for running. I'm happy to answer any specific questions if you have some.