Dairys here use several different types. The funny thing is, it doesn't seem to matter what they are using this year, SCC counts have gone up nearly with everyone. I think as do most of the farmers, that the constant wet has caused some of it. The pack barns are wet, the pastures are wet, the confinement ones with free stalls are wet.... I will have to take a "poll" of some and see what they are using and if they have changed. I still see some of them with good old iodine that do okay. Some here will change to an "winter teat dip" because of the emollients for the teats in cold weather.
The "udder gold" ones that you have to mix are still used on a few and have one that uses something that is "flourescent green" and stains any and all clothes it gets on.
Have alot of dairies gone to hydogen peroxide for pre dip. The 2 best farms I test for run under 100,000 nearly all the time. But I've got a few that are up near the limits and I would not drink milk from the tank. Most run under 200,000 most all the time. With the new regs coming out I think there will be a few more going out. Or maybe at least getting rid of the problem cows. I have yet to understand keeping some of these high cell count cows "because she makes so much milk"....