I came across this AOS brush that my son gave me years ago. I think it's a pure badger knot. Here is a picture of it sandwiched between a Wee Scot and a 28mm Chief. You can see that it isn't much larger than the Wee Scot. Very little backbone. You could almost say somewhat floppy. Now look at the lather it created: Incredible, right? This brush, bowl-lathered Krampert's Bay Rum soap like a champion. Size really doesn't matter. Does it matter to you?
IIRC, this AOS badger was my first badger, and I was very disappointed with its its diminutive size. When I complained to the seller, his reply was; what were you expecting for $20.00? I hated that brush and IIRC, I dropped into one of the travelling boxes. But I wonder now; how would I feel about it now?
I prefer my smaller brushes, 19-24mm, as I find them to be more maneuverable, easier to handle and they make a lather as good as the bigger brushes.
I like my 22 mm synthetic as much, if not more than I like my 28 mm synth. I had an Omega pro 48 and it was too large and I sold it, I wonder how I'd feel about it now.
I have an Omega Midget that lathers like a champ. Some small brushes definitely punch above their weight.
I used a smaller boar brush today. I call it the lather monster. It did a veddy nice job. It will even work up modern Williams. I have a ER 104 that is a favorite. I love all size brushes. The smaller ones do just as good a job I agree. On a side note I moved my AOS knot into a Fuller brush handle. It is a great brush!!
Long long ago and in a land far far away there was a company called Baton that made great shaving brushes. That one is a Best Badger from about a half century or so ago. The land was the US, home of fantastic shaving brushes from Plymouth and Opal and Baton and Erskin and EverReady and MadeRite and Rubberset and Peerless and Aristocrat ...
I picked up a couple (one white handle, one black) Omega 10086 boar brushes mainly for travel years ago. However, as I like to work up lather in the container the soap comes in, these little guys are my break in brushes. They easily make enough lather for a 2 pass, minor touch up shave. Less mess than when using a larger brush. Very easy to control. When the puck is about 1/2 used up, I switch to a larger brush.
I used Vulfix brushes for over twenty years and loved them. Even though they're reputed to be extremely floppy (and they are), I never had any problem creating great lather even with milled soaps and hard water. I still have two and use one occasionally to give my synthetic a rest. My favorite is the 374 in super badger at a scant 20mm. The trend seems to be toward huge 26mm+ brushes, especially with the synthetics. Personally, I don't care for brushes that large. And I also like some flop (my synthetic is a 23mm Plisson).