Pathfinder 2E is very GM friendly
I started playing with Pathfinder Second Edition about a year and a half ago. It's an elegant system, that seems to perfectly mix the best parts of Pathfinder 1E, with some of the best parts of DnD 4E and 5E, with some really tight numbers math under the hood. Pathfinder Second Edition has such tight numbers that it relieves some of the challenge with balancing encounters.
I'm currently running my own campaign in PF2, and have come to love the rules for building encounters.
PF2's system isn't built around an adventuring day like in 5E. It basically assumes that the PCs are fighting each combat at full or nearly full strength. Many of the cool things PCs can do are either at-will powers (can be used every round without use of resources) or per combat powers (having a 10 minute recharge/cooldown). This is a mechanic I remember from 4E, which was widely unpopular for being too 'gamey' at the time. PCs also have access to larger health pools and, often, essentially bottomless out of combat HP recovery if they're willing to spend the cooldown time.
The XP Budget makes it easy to design an encounter of varying difficulties.
Let's take a recent dungeon I made.
The plot here was that the party was investigating a haunted basement under a ruined priory (put very simply). I wanted an easy fight to get the party feeling confident because I knew I was going to hurt them later. They were a party of 4 level 4 PCs, so I started them off against a group of four level 2 animated armors, which they clowned on easily.
A few hazards and puzzles later, I wanted the party to square off against a classic mid-dungeon Miniboss. I grabbed 2 level 4 shadows and a level 4 caster NPC (following the elite enemies template), and had the perfect difficulty level.
A bit further down the dungeon, I wanted them to fight a large, big boss. So, I used the Boss and Lackeys model to pit them against a level 7 boss joined by four level 1 mooks (the party had leveled up mid dungeon). It was technically the same exp budget, but the spread of it the mobs made it feel dramatically more tense, despite taxing their resources about the same amount. The boss being two levels higher meant that they would resist more assaults on their person, while also critting half the time. Enough to scare my players.
It's a pretty fun system to build around, if you like some more crunch. Yet, once you figure out how things work, that crunch is quite smooth, without losing much in the way of complexity. Plus, every fight can be balanced internally, while letting PCs feel punchy and tough every combat.