I voted that polyamory and monogamy are equally good. This is mainly stated in principle. There's a lot of anti-non-monogamy conditioning out there that skews the results of how the two lovestyles compare in practical terms. Many monogamous relationships are just people unhappily trying to make themselves fit for a box they weren't designed for, but I don't feel I can say for sure how many.
In principle, if both people truly consent to the monogamous arrangement, and are truthful and loving towards each other, then there's no reason to say it's less good than polyamory. I've known polyamorous relationships that were worse off than some of the monogamous relationships I've seen. Further discussion on this topic is welcome, for those who are interested.
Love means never having to say, "Put down that meat cleaver!"