I have a Haake brush, but learned why they call them "haate" brushes (shedding hair on an emulsion project - ouch!) Though I understand you can beef up the thing with crazy glue.
The Liquitex brush is about as perfect as I can imagine, very thin so it doesn't suck up tons of emulsion. Note they come in a few sizes, too.
By the way, for coating large sheets with a brush - those single-bulb red LEDs that got popular on APUG are the stuff! I have one in a gooseneck lamp that I can angle off the surface and really see defects and strokes. Absolutely love those bulbs! The find of the year - my darkroom is so bright now.
Here's a link if you're curious.