We use Covenant Eyes on our macs and have for a couple years now, no complaints, good customer services. It looks like Web Chaver uses Covenant Eyes as it’s program, i’m not really sure what else Web Chaver does. It gives exactly the same reports as CE but with their branding.
The biggest problem you’re going to run into on a mac is that there are VERY little web filtering programs that work with a mac, the only part of CE that is going to work is the accountability reports that log every site you’ve been to.
For filtering we use OpenDNS which you install on your router (they have easy to follow instructions), which is more secure any way, as it doesn’t matter what computer or mobile device, if you’re on my network, it’s filtered automatically. From OpenDNS’s website you can set many different ways of filtering and keep logs too. It’s all free because it’s open source.