DMARC vendors for O365 - thoughts? experience?

Microsoft lists in their Microsoft Intelligent Security Association (MISA) catalog a handful of vendors for DMARC, since it's not a native offering from MS. The vendors are the following:
Demarcian
Agari Brand Protection,
Red Sift on dmarc
Valimail Enforce

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Does anybody have experience with any of these vendors, thoughts, opinions, cheap expensive etc? We're starting to dig into this territory and I'm on the front to research these offerings. Thanks ahead of time!

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