I use paint brushes daily, I usually use a filbert or a flat. My go to size is 8. For 3 decades I have used well made natural bristle brushes. I have a few really fine sables, squirrel hair, and mongoose hair brushes that I use for water color, and oil portraits. My daily landscape brushes are mostly hog hair.
I take excellent Care of my brushes, and they last for a really long time. Above are the brushes that have been my go to brushes for the last year. I recently started a painting and noticed that the brush was shot, the bristles had lost their ability to hold an edge, and they were droopy. I reached for a second brush, which was also shot. So I looked through all the brushes that had been in circulation. Three were in almost perfect shape despite constant use. They were rosemary and co. Ivory filberts. Synthetics! I was ordering some portrait brushes about 4 years ago from Rosemary and Co, and the person on the phone asked if I had tried the Ivorys. I told them I didn’t usually like synthetics, but would give them a try, I ordered only 3. Initially they were fine, no better or worse than a bristle. However they have held up MUCH better than the natural bristle brushes.
My current 3 favorite brushes are all Rosemary and co Ivory brushes. Filbert size 6,8, and 10
Here they are, after hundreds of paintings! Still going strong. If you like control or are new to painting, I recommend a short flat or a filbert. If you like a looser painting, I reccommend a long filbert or flat. Egberts are the longest bristles and will give the loosest most lyrical strokes.
If would like to know more about paint brushes, here is a well written article that covers just about every type of brush. There are so many good brushes out there, but these ivorys are kind of like buying a Honda, dependable work horse with lots of miles in it.