Headcovers: Leather vs Wool Knit

I currently have leather headcovers made by Sunfish and they are great. They are black with a white stripe and go well with my Titleist carry bag. If you get on Sunfish mailing list they have specials - I bought a set of 3 for $85 a year ago. It came with Driver, 3 wood and hybrid covers but I called them and they substituted a 5 wood cover for the hybrid. I've also bought Ohio State and USA hybrid covers from them. They are well made and the company is great to work with and they are made in the USA! I like the looks of the knit covers but they get dirty and some tend to stretch and fall off and then I'm walking back to pick them up.