So I have been looking for a new commuting backpack/ general use backpack. Now I just want to specify I am looking for a BACKPACK I am not going to choose panniers or a messenger bag.

Just for a little background I am currently using a Kelty RedWing 3400 but I have found that while biking it just simply is not a good bag. It is simply too large and unruly to manage. That being said I do need a good amount of storage space so that my bag can act as a riding bag, commuting bag, grocery bag, and a bag to transport my books. That being said I am looking in the 27-32L range of sizes.

I should also note one of the important things to me is how a bag feels when it is sitting on my back, I don't like it when bags flop around like crazy, I also enjoy attachment features (Helmet carriers, pockets, access flaps).

Because of this I have narrowed down my options to a few bags and I was hoping that people here could give me a few first hand experiences and feelings about the following bags (Or new bags if there are some that are very similar to these bags that I haven't )

Ortlieb Flight 27L
Deuter ACT Trail 32L
Deuter Trans Alpine 30L

I like the Ortlieb's full weatherproofing but it seems to lack the features of the Deuters and being more expensive and smaller then the deuter's makes me lean away from it but I want to know how comfortable it feels on longer rides?

The Deuter ACT Trail has a good mix of features but I question if it carries it's weight correctly for longer rides (Anyone have some experience?). I did get to try one on though and it feels VERY comfy and secure.

The Deuter Trans Alpine is what I am leaning towards. It has a alot of features I really like (Helmet holder, bottom access, pockets, seperable lower and upper main compartment). Yet I cannot seem to find any store that carries it so I can try it on. Anyone want to give me some experience on how comfy it is?

Also I was debating doing the airmesh thing that Deuter does. I know someone suggested a bag series that uses the airmesh and Ortlieb's waterproofing but because the airmesh makes the back of the bag bow in towards the pack it makes it harder to load things like books and laptops into the bag so is there any bag that has an airmesh that doesn't bow the back of the bag? That may just be wishful thinking.

Anyone have any suggestions here? I am very heavily leaning towards the Trans Alpine but I would like some info on how it feels compared to other Deuter bags/ how well it carries it's weight when fully loaded.