The FAXX brand practice mute is very similar to the Best Brass mute - for much less money. You can't beat it - simply try it. It's as free blowing as a practice mute gets.
Since this is the first practice mute I've ever used, I can't make a comparison to others. I purchased this one based on descriptions of other brands of practice mutes. What I can say, though, is that compared to practicing with a regular straight mute which I was doing out of necessity, this mute makes practicing feel more normal. The air is free-flowing and pitches are stable. It's more quiet than the straight mute which makes it perfect for our small house. For the most part it stays put in the bell. That it loosens occasionally may just be particular to my horn. I'm very pleased with it and, for the price, would suggest it as a good compromise between the most and least expensive brands.