A friend asked me about brushes earlier so prepare for a waffle.
I do about 90% of my painting with a size 1 brush, using a 0 or 00 (sometimes written as 2/0 to be confusing) for detail - that roughly lines up with M and S from GW I think. I've recently starting using a size 4 a lot more, as it holds more paint.
Most of the higher end brushes use Kolinsky Sable, which is a type of Siberian weasel (and thus not vegan) - though other natural and synthetic ones are becoming popular, not least of all because the price of the fur has been increasing.
For the longest time I used Winsor & Newton Series 7, a watercolor brush from a really old English brush manufacturer. Christmas last year my partner got me a set of Artis Opus brushes that I have mostly switched to (also supporting local, they are manufactured in Stockport, the founder of the company is also one of the owners of Element Games). I did also get gifted a Raphael 8404 last week by a friend, I've yet to try it but it gets compared very favourably to the W&N.
For the most part it's personal preference - I like the Artis Opus ones as they're just a tad longer than the W&N , and also if I buy them from Element there's no chance of them being fake, which is a problem W&N had on Amazon in the US for a while...
Links
Here's the three:
https://elementgames.co.uk/paints-hobby-and-scenery/artis-opus/artis-opus-series-s-1-brush
https://www.jacksonsart.com/winsor-newton-kolinsky-sable-round-series-7-no-1
https://www.jacksonsart.com/raphael-kolinsky-red-sable-brush-series-8404-size-1
(Note for the W&N series 7, they do a normal and a miniature version - you want the normal one, despite it's name the miniature one is too small for us, it's for painting tiny watercolors).
Brush Care
This video is also good for teaching brush care:
https://www.youtube.com/watch?v=GeDwTY7C9xs
I'd most agree with him on the soap, it helps keep brushes alive and working for longer:
https://www.jacksonsart.com/the-masters-75ml-brush-cleaner-and-preserver
Others
I also use a lot of cheap brushes from amazon, something like this:
https://www.amazon.co.uk/gp/product/B08QFWBQXC
They're fantastic for basecoating, doing large volumes of stuff (like terrain...) or even work fine for some detail work.
The GW brushes are also fine (apart from the super cheap ones you get in starter sets or for free, they are garbage) - their artificer ones are made by Windsor and Newton I believe, and I really like their drybrushes (though, you can get away with just cutting the tip off an old, ruined brush just fine).
Conclusion
In general brushes are a consumable - in 2020 when I painted all of those Tyranids I went through one in 6 months, though if I was painting less or took better care of it it'd last a year plus. They can be expensive, though I like getting them as gifts as it's a way for people to gift me hobby stuff but not add to my backlog...
