Registry memberships in Canada?

So I have a new mare…registered with GOV but also has her STER with KWPN, also is actually branded KWPN. She is also in the main studbook for the Hanoverian Verband.

Her previous owner registerred/branded all this mare’s foals as Hanoverian (at inspections).

What are the pros and cons of each of the 3 registries if I was to breed her this year. Stallion is approved Hanoverian

I’ve never been a member of any registry before so this is all new to me!