"Z" bends, or "U" bends are not good for a aerobatic model. (IMHO)

I like ball links all the way around, However the plain old clevis work fine for most applications.

Z-bends work fine, but can be sloppy. Never tried a "U" bend.
The "L" bend and plastic keepers-----never again. I've had 2 of them let go. Don't know how, don't know why. Maybe even my fault, but never again. (well except on my 2 meter floater gliders