well, it very much depends what you needs are.
It you need to carry around a 15” laptop (I don’t) you can’t escape its dimensions.
Also, if you carry the camera with one lens (even a zoom) it’s a whole different story than carrying a camera several lenses and things that you may need.
I truly hate ( and I have all my long photographic life) to pile up lenses and camera in a small space. All ONA are, for this reason too small for me because the majority of so called messenger bags will need you to, at some point place came and lenses in layers. Of course this means that at some stage you will have to juggle at least three things with one hand ( the camera, the lens above the one you need and the lens under the lens above, which, at some stage or other, you didn’t need as opposed to the one under which is the only one you want).
So My bag of choice is large. Would allow for a laptop ( currently I have no need for it and I have only once had the need for an assignment to carry a laptop to show the journalist the pictures that I was taking for her article). And if I am going to stay away for several days I can also put clothes and other items or simply put all my photographic equipment (and even in such a large case I will end up with a couple of lenses arrayed in a layered fashion.
So my bag of choice (which you can see above) is made of leather,witha waterproof material on the protective flap, large, not incredibly expensive, reasonably waterproof, carries a laptop ( or a change or two of underpants and t shirts for just in case your luggage isn’t there when you arrive) and it is reasonably mistaken for any ordinary piece of luggage.
But yes, it is large, no two ways about it.
the popular expression wishful thinking is an oxymoron!
To all TAPATALK users
As a form of courtesy towards your fellow users of this forum, PLEASE remove the obnoxious tapatalk signature, it adds nothing to anyone’s contribution and it is only a sneaky way used by tapatalk to push their product by polluting each forum participant with promoting their products with unpaid advertising for their software and the brand of your phone. Removing it is easy and it is an act of courtesy that shows respect for all those whom are annoyed by this pointless feature. This is not a personal attack to you, the annoyance is caused by tapatalk and the phone or tablet brands, they are getting all the exposure and you gain nothing by this.