I use a Leather ONA Union Street as my daily brief case. In it would be a 15" MacBook Pro, 12.5" iPad with case & keyboard attached, various external HDD x 3, Usb memory sticks x 5, pencils pens, cables .... lots of cables (thunderbolt 3 ).
I do not pack a lunch (eat out) and generally have no need to carry hard copy documents or other reading materials in a physical sense during my daily routine.
With all the above I still have plenty of room to carry a M10 with 3 lenses.
Weekends I have other ONAs, both the Berlin II and Princess Street in Leather, picked up on eBay lightly used at a huge discount off retail.
The quality and durability in the Union Street impressed me, hence I sought out the other models in leather but in hindsight the smaller bags are a little heavy when walking with either of them
all day long. Nothing back breaking, but you just notice it being heavier than say a Billingham Hadley (another fine bag)
My preference of the smaller ONAs would be the Berlin II, I prefer the more secure front pocket arrangement.
Plenty of room in them to carry either a 12" MacBook or 10.5"iPad along with a M10 and a good selection of lenses and accessories.
The Fogg bags look fantastic and very smart, perhaps a little "too smart" to attract the wrong attention. By all accounts a super bag with unfortunately a super premium price tag.
No doubt, you'll try many until you find your ideal bag, that's all part of the fun. .