It really is a never ending quest for me. I've got two backpacks, one sling bag, and a mess bag (which is up for trade). Each has their strengths and weaknesses- meaning I'm constantly packing/repacking depending on weather or cargo hauling needs.

Photos are blocked at work, so now that I can see them thanks for the Apex/Osprey review...I wonder if I can find the comfort and organization of the Apex with the cooling of the Talon...

I find making a pile of what I'm going to carry and then picking a bag helps avoid repacking like that. I know just what you're talking about!

Has anyone tried the Osprey Momentum? I think it looks pretty well thought out for my needs, anyway:

Osprey Momentum 26

I use a kelty redtail. Has a lot of cool pockets for stuff that you might need on your way. 2 side pockets that can hold extra water. 2 straps one goes around your chest the other goes around your waist. well built I have had it covered in mud sand and crap from the roads. It will wash right off. It looks like brand new after I used it during winter with no rear fender and you could never tell I have worn the bag before. hope that helps.

No experience with it, but noticed something interesting following your link. Click on the specs tab and you'll notice they have two sizes (S/M and M/L). Both have the same stated product dimensions...

If you can afford it, go right on ahead and get it. Then you can do a review of it here.

I own a Kelty Redwing 3100 that I use for groceries, travel, and pretty much anything non-bike related. I've had it for about 4 years, it's indestructible but it's also so large I can fit a 737 inside of it.

So when I got a bike, I went to REI for something smaller and better for a bike, and got the Novara Commuter Backpack from REI. It fits all of the tools I need, all of the other random stuff I need and a few small things I may pick up during the course of a day. It's laid out better than the Kelty for commuting. It has worked out quite well. It's yellow, but not an obnoxious yellow and it appears to be pretty bomb proof. I stopped at a liquor store on the way back from work and the clerk said "that bag looks pretty durable" as I attempted to shove several large bottles of beer into it. Seems to be the general consensus.

I was at REI today and I did like that Novara Commuter and next to it was a KoKi Vespa commuter bag. I really liked it, mostly, but I think it would be too small for me. Here is a link:

KoKi Vespa

It just felt expensive to try thinking it might be too small. Still trying to locate an Osprey Momentum I can play with in person to see if I like it.

another vote to this pack. I have one. I like it.

I tried on one of those at a store recently. . . It was ok, a little narrow for my purposes, though.

I run a REI Flash for my 10 mile commute - http://www.rei.com/product/778466/rei-flash-18-pack

It's super light, packs down to nothing when I don't need it, and has plenty of room for my change of clothes/lunch/netbook. Also is hydration system compatible. My wife and I also use it as a daypack when hiking/backpacking.

I used to use a larger backpack (also REI) and more recently two different Timbuk2 messenger bags - the Flash beats them all in versatility and comfort. Best of all it's only $30 (and cheaper if it's on sale or you have a dividend to spend!).

jansport?

My gf has one of those, and I find the L L Bean Stowaway more comfortable and easier to use with the external pockets. Plus, it's got retroreflective parts for the night commute. They're both good packs, both the same price, almost the same size, and just about right for my regular commute.

I also have used the Kelty Shrike both on and off the bike, and it's the most comfortable pack I've ever worn. Especially when carrying heavier loads.

another vote for the REI Flash 18. It's a great pack. I use it for day hikes too, and hydration is optional.
I also have a Topeak seatpost rack with a Novara trunk bag. The advantage of the flash 18 is that it weigs nothing and rolls up to nothing so I can commute with the trunk bag and then go grocery shoping on the way home and fill the flash 18. The combo is versatile.

Those Flash packs look good, but for someone looking to replace seat bag and the rest and have one consolidated place for tools, tubes, and clothing, I'm not sure how it would work.

The Flash has an internal pocket system - one big sleeve against your back big enough for a hydration bladder, and on the "front" of that sleeve there are a number of pockets. They're not the easiest to access, especially when you've got other stuff in the bag, but they hold things in place. I have a pump, multitool, spare tube, cell phone, wallet and keys all stowed in the various inside pockets for my commute, with clothes and lunch in the main compartment.

I do wish the pack had a few external pockets but like I said, for $30 I'm pretty happy.