I am assuming you are comparing D&D5e and pathfinder 1e, if we are talking about Pathfinder 2e, it has more robust and balanced game mechanics. At least for me and my table, it´s vastly superior to the other two.
I've just started getting into the world D&D and Pathfinder since BG3 early access was launched so I'm not too sure the editions I'm reading. I pretty sure the Player's Handbook is 5e. Not too sure on the Draconomicon though. I also didn't know there was a Pathfinder 2e. I've just been reading the Core Rulebook. The books I've been going through are D&D: Draconomicon, Player's Handbook, and Eberron and Pathfinder: Core Rulebook, and Campaign Setting Technology Guide
I've also been going through the sites D&D Beyond, DND 5th Edition wiki, and d20pfsrd.
Do you have any recommendations for me?