I use Wolf Fang earth anchors. I have never had an issue if properly set. Thay can be hard to hammer in near roots or rocks. Also if soil is really wet or loose, pay special attention and set them good. You will know when you pull on them if they will hold.
If I can't pull them loose pulling straight up, a coyote will never pull them out pulling sideways. Better buy or make a puller to remove them and even then, you will break some off.
