Ezoic names 8,460 sites in its seller file against PubGalaxy’s 2,610, and 12 publishers run both on the same pages. Reach is only half the question though — the authority spread below shows what kind of sites each one actually carries, which is what determines whether you would be accepted and what the inventory is worth.
PubGalaxy is the more selective of the two, with a median authority of 18 against 7. The overlap figure is the practical one for a publisher: 12 sites already treat these two as compatible rather than mutually exclusive.
On 5,850 more sites than PubGalaxy — the larger footprint of the two.
Median authority of 7 against 18 — more of its sites are still small, so a growing site clears its bar sooner.
They treat the two as compatible, not either/or. The “Also uses” column on either network page lists them.