I would say PF1 is a bit more streamlined than 3.5 in general. Especially it has a quite good online srd: d20PFSRDI said 1e, but I want to unpack it a little for fairness:
1. I am not directly very familiar with PF1e, but I was familiar with D&D 3 and 3.5 and nothing I've been told suggests they're different in any significant way in complexity as such;
2. I consider the more special casing something has the more complex it is, and I actually think that weighs in as much more more than actual complexity in general mechanics.
I would say PF1 is a bit more streamlined than 3.5 in general. Especially it has a quite good online srd: d20PFSRD
When you look at that and at classes like a fighter: Fighter – d20PFSRD then the base classes are normally easy to understand (not truenamer strange things), but it also has many advanced options etc. (which make the classes long like the advanced weapon feats).
well the feats in pathfinder are all +1 to something. If you forget they are called feats then they look suspiciously like someone took 3rd edition advancement and squished it WOW style to make the numbers stay lower and easier to control. It's mathematically far better, but the way they implemented it enhanced pathfinders 1e focus on tactical focus instead of 2e's strategic focus making combat very much like an old school chainmail game. Very controlled with a very predictable set of options every time.What made PF1 easier for me to read and understand was that it was a continuation of 3e D&D. As a result, it didn't seem that complicated. The rules between 3e and PF1 were roughly the same. Character generation was pretty much the same. Everything in PF1 didn't require a feat.
Featfinder (aka PF2) required a feat for almost everything.I thought people hated bloat in their RPGs.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.