The best wash mitts, that will limit potential damage the most, are wool mitts, but they need maintenance to keep them at their best. They need to be dried well, and combed afterward. CarPro Merino Wool Mitt for example.
Genuine Wool Mitts - very safe, deep pile, but need a lot of care
Microfiber - safe, deep pile, dont need a whole lot of care - very good value for money if you but a quality on
Noodle Mitt - not so safe as there is no real pile, dont need a whole lot of care
Sponge - WHAT? :P
The Microfiber Madness Incredimitt is very good - very durable; using mine about 2.5 years now. Nice length of pile, built in sponge so holds lots of water/shampoo. Easy maintenance; wash it out with fresh water, hang it up until next use. I dont care for mine as well as I should (usually gets thrown into the bucket after a wash), and while it needs replacing, not bad for 2.5 years of abuse.
The choice of shampoo would also be a factor in limiting potential damage - its not all about the suds, but rather the slickness they offer.