I have used both the split rings and zip ties. There are issues with both.
Cons... The split rings come off and the zip ties don't.
If it is imperative that your poultry stay marked (as in banded ) the split bands may not be a good choice. I have found them in the floor of the coop and not know who belonged to them (I think that is the safety idea)
. I like the zip ties the best
BUT you MUST monitor them. It is not so much the cost as it is the dependability. But the chickies grow up before you know it and
will out grow their zip tie -
they will never ever come off till you cut them off.
The zip ties must be changed several times before the chicks fully mature. When they are several months old you can usually put it on loose enough to not have to change them again. (but should still be checked regularly). I order them in a
rainbow of colors and some times use 2 or 3 bands of different colors for different reasons (age, breed, breeder).
But
PLEASE if you use zip ties, it can't be said enough,
check them, check them, check them.
Just my humble opinion