Looking for a good quality 25L daysack. Any recommendations?

So I bought a cheap Regatta daysack after my previous (cheap Chinese import) bag fell apart at the zip. The Regatta bag looked sturdy, felt comfortable, handled everything I threw at it, and broke after 3 months.

I want a bag that can comfortably take a DSLR, an A5 sketchbook and watercolour box in its main part, has a couple or three extra compartments I can stuff with pencils, sandwiches and strong drink, and for the love of God doesn't rely on a zip to fasten it.

If the straps are comfortable and don't saw into my shoulders like twin hacksaws, that would also be nice. I would prefer this bag to be of a sober and modest colour, without any logos or advertising on it. Budget up to £50, unless you all laugh and say that's nowhere near enough, in which case I might reconsider.

Hoping you can help me, BushcraftUK.