I have two adapters, a Canon plain adapter and a 3rd party control ring adapter. Both work equally well. The adapter is just a metal tube with pass thru contacts and there are plenty of 3rd party ones to get rather than whine. Canon does not want to let 3rd party makers take away their big profits on the adapters, they will catch up soon.
Many people posted that they were buying a adapter for each of their lenses. That was unexpected and unnecessary, it burned up stock right away.
My $99 Viltrox control ring adapter works fine, I have backorders on refurbished ones but I don't know if / when they will appear.
Shop B&H's in stock, large inventory for fast shipping, great service and everyday low prices on ef-rf adapter . For more info, please call 800-947-4415
www.bhphotovideo.com