I've just treated myself to five new miniature painting brushes.
My preferred brush of choice is the No. 2 and No. 3 Rosemary & Co, 401 - sable/synthetic mix with the long handle. I find that the sable/synthetic mix works best for me as I like the 'spring' that the synthetic bristles give and I can abuse them more than a pure 100% sable. I also like the feel of the longer handle; although this is just personal choice as the heads are the same on the standard and long handled options.
Details of Rosemary & Co can be found here.