Nearly a year later, Mozilla is still promoting Onerep (krebsonsecurity.com)

I use Optery and am happy with them. I can't offer a meaningful comparison to other services, but they seem transparent and responsive to user concerns.

Disclaimer, I did some contract work for Kanary, but their approach is much more transparent than most other alternatives. They recently launched an app that automates the process on your device locally, so you can see exactly what actions they’re taking on your behalf. Plus doing the opt outs locally helps with the captchas and other rate limiting measures these people search sites put up to block auto-removals.