Neither are convincing for claims of "overt bias", and even IF there was a huge bias in the selection of statements to rate, then this only means ... a bias in the selection of statement to rate, and doesn't actually say anything about the truthfulness (or lack thereof) of the actual fact-checks. A partisan "we-rate-republicans.com" and "we-rate-democrats.com" could be 100% accurate in their ratings. "Biased" does not equal "false".
I do think that "politicians from one side are rated much more frequently" is a good reason to take a close and skeptical look by the way, but that needs to start with "are politicians from that side actually untruthful significantly more often" as a baseline.
So I would rate your post as "false" for 1) making a claim that's completely unsupported by your evidence because your evidence actually makes a different claim, and 2) being weak evidence in the first place.
Politifact is a good case study. Academics have repeatedly published data since 2011 [1] and most recently 2023 [2] showing an overt bias yet it's still used as a reputable source to fact check things in many places on the internet.
[1] https://smartpolitics.lib.umn.edu/2011/02/10/selection-bias-...
[2] https://dukespace.lib.duke.edu/items/8f9a6f3b-efd7-46f3-b4be...