For the size, I'd like something in the 12-15L range with a normal 20L backpack silhouette and a thinner depth. Material-wise I'd like the lightest durable fabric with some amount of water protection. It doesn't have to handle falling into the water, but light/medium rain shouldn't be an issue.

I hate top loaders... panel loaders are way better. I'd like the zippers to go all the way down, too, at least on one side.

I like to have lots of 3D pockets (so that they don't interfere with each other), a big main pocket with a laptop sleeve on the back (I'd love for the sleeve to be lined on one side with semi-rigid plastic to make it easier to stff the laptop into a full bag). There's really no amount of pockets that's too many. I've actually looked at getting a camera bag because they're all small compartments.

The straps of the pack should also have pockets. I'd love to be able to store my headphones (maybe some cool pegs to wind them around) and flashlight there. Camera would be great, too. 

Items that don't store well in my backpack now:

• Folding sunglasses get scratched if they share a pocket, but they're too small to have their own
• Camera is never as easily accessible as I want. Neither are headphones.
• My misc. cables pocket is a mess

I also think that the interior should be a fluorescent color. True fluorescents actually convert invisible wavelengths of light to visible, so I think a fluorescent color would make it easier to find things at low light.

Not super important, but I like the idea of little clips at the end of each zipper to clip the zipper to. Makes it so that in crowded public trains or whatever, you don't really have to worry about someone sneaking into your bag.

An integrated rain cover on the bottom (like the Deuter 28) is a good idea and makes it so that you don't have to waterproof the whole bag.

Most packs do not come with the GoRuck GR2 / REI Overnighter style 'luggage' zipper that zips all the way open. It's like a panel loader, but just more zipper.   I find that style very very useful.  Also making the interior a very bright color is fairly useful too. Something like the REI overnighter, but with a laptop pocket, clips with a metal latch vs plastic and a lighter fabric to save weight would be fairly useful.

hmm, I'm interested in something custom as well. Right now the only two packs I'd consider are the goruck gr1, goruck radio ruck, or 5.11 rush 12 (which i own). The reason isn't aesthetics - it's because these packs keep the laptop in a separate compartment, and are still relatively durable, and the zippers go all the way down.

The 5.11 rush wins over goruck in terms of organization, and it also has a separate lined pocket for glasses. Sadly, I have to switch away from my rush 12 soon since it doesn't fit a 15" macbook (it's perfect for my older 13" though).

My biggest complains of the gorucks/5.11's are the lack of water pockets - adding on an extra molle hydration pack looks really nerdy to me. Also, I'm not the biggest fan of army-colors, something lighter colored and not black or camo or army green. Light sand colors are currently what I rock, but I'd love a rugged pack that's aesthetically pleasing/modern.