mysunwolf
Herd Master
That first one looks pretty wicked and likely harder to put on. But I've never tagged an animal so my opinion isn't worth even $0.01
Ha, yeah the first one looks terrifying but that is what we use. It's smaller than my pinky finger and looks like a small, thick "hoop" earring on the sheep. Very easy to put on, easier than the other tag systems IMO because the applicator is smaller and easier on my small hands. I have used all the above systems and stick with the metal ones because they're discreet, and did I mention free? Lol.
Their downsides are A) hard to read from a distance, B) they snag on stuff really easily because they're closed-ended so if your sheep are browsers and very active they tend to rip through the ear, C) the shine wears off quickly and it's harder to read the numbers even up close.