I've had a Nissin Di622 MkI and I only sold it when I updated to a Canon 60D and a 650D for the wife. It needed a firmware update to be fully compatible and I couldn't find anywhere local to do it. The MkII is compatible with all the current models AFAIK, I've used one on my 5D3 and it worked very well.
I've also got a Nissin Di866 MkI and a MkII that are also excellent. I mostly use them as off camera flashes triggered by my 580EX II, but the Di866's are fantastic on camera flashes too. I use the MkII on my 7D, my 580EX II on my 5D3 and the wife has the Di866 MkI for her 650D so we're well covered. The 580EX II is probably the best flash I've got as it's fully compatible with all the features on my 5D3 and 7D but the Nissin's are close despite being about half the price.