I have a Semogue 1250 that is my absolute favourite value brush.
Omega 10066. When I first started wet shaving I was researching brush after brush and at first I was convinced that badger was the only way to go but I was on a pretty strict budget so the only badger brushes I could afford were the cheap ones on Amazon and they didn't have great reviews and I didn't want to get something that wouldn't last. I was watching a video from Nick Shaves and he talked about how he loves his Omega 10066 so much and I started to look into boar. I found an Omega 10066 online for $6.99 plus shipping. I had bought some blades, soap and a blade bank from the same site to bundle for shipping purposes so I'm not too sure how much it was with shipping but it was very reasonable. I use this brush almost every shave. It's not just a great brush for the money, it's a great brush in general.
Very simple. Can't speak to Omega but the Semogue OC boar (($28 if you shop online) is by far and away the best boar value brush I own.
Omega S-Brush gets my vote as well.
Real simple for me, Omega S-Brush...amazing value and an amazing brush!
Omega S-Brush for synthetic
Omega S brushes! For less than $10 they are amazing.