I never really liked fusion because they tend to shed a lot and that glue can be hard to get out of the hair.

 

I used to love Eurolocs and did them exclusively on all my clients for a year or two.  But then I started to see damage to their hair.  Eurolocs are a little different than all the other 'ring' methods in that you use a special tool and double fold the ring.  (first fold it like a book, and then fold it in half again).  By double folding them they do stay in well but you need this special pointy, pincher type tool to pry them open when it's time to remove them. 

 

I think that myself and other stylists who had used the method agreed that opening the ring with the pincher tools totally sheds the natural hair, causing extreme breakage.  I don't think that there's any other way to re-open that double folded ring either.