Suggested reading order for pathfinder books

[Xervous]

In terms of most impactful or otherwise foundational rulebooks and splatbooks to least what reading order would the playground suggest for procedurally devouring PF1 content?

[Palanan]

The APG is usually mentioned as one of the most useful after the CRB, so you might start with that. Ultimate Magic would be a good follow-up, since APG + Ultimate Magic gets you some of the best classes outside of the CRB. Advanced Race Guide covers the majority of playable races and is a lot of fun to look through.

After that, it really depends what you're interested in. I enjoy the Adventurer's Guide, which is a compilation of PrCs, but most people consider those nonessential in Pathfinder games and might not include this one. It also includes a lot of lore for each of the organizations tied to the PrCs, which might not be as relevant if you're not using Golarion as your game world.

So, reading order depends on taste and your specific interests and/or goals. Anything in particular you're looking for?

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[Xervous]

My goal is to gradually familiarize myself with system to the point that I could play, GM, or otherwise comment on various mechanical aspects of the system with high mechanical competency.

If the opportunity to play in a PF game comes up in the future I’d like to have the same comfort level as I do with 3.5e, able to gauge the overall party power level and structure my character to faithfully express the traits I desire while keeping it in the same ballpark as the other characters.

On the mechanical structuring part I am intrigued by the subtle differences between 3.5 and PF1. With much of my current gaming being in the realm of full on homebrew systems the similarities of 3.5/PF seem to promise that the effects of the various differences will be easily isolated for analysis.