Reddit mentions of KOLINSKY SABLE Professional Artists' Round Paint Brush short handle 1010 Russian Roubloff (00)

Windsor and Newton 7s are the best brushes that I've used. They're also the most expensive brushes that I've ruined (screwed up my last two by not waiting long enough to start painting after a superglue repair and glued the bristles together with the fumes) so I also have a number of less expensive, good quality brushes.

Blick's red sable brushes are a great bargain brush. When you buy them online they're about $3/per. They're a little more temperamental than a W&N, but they're good brushes once you understand how wet is too wet and you can't beat that quality to price ratio.

I recently picked up a few of these Rautloff Kolinsky Sable brushes, my initial impression of them is favorable. I've painted a grand total of one 28mm figure with mine, but it feels like I'm painting with a good quality brush. The bristles are longer and thinner than you would expect from a brush of their size rating (they're closer to a "liner" style brush) which is worth keeping in mind if you're looking for specialty brushes. The link is for a Russian importer though, so expect a long delivery time.

Also keep in mind that you want to have a decent stock of lower quality synthetics for tasks that cause heavy wear or for materials that could damage natural hair (resin medium based paint, glue, etc). Specifically, I like Royal and Langnickel's Zen brush line for flat drybrushes, they have a decent stiffness and they're about the right length as well as being readily available. Michael's Artist's Loft Vienna series brushes are passable, they are synthetic so they will hook, but they're the best in-store brush I've been able to find short of those Blick Masterstrokes.