I’m just past act 1 in Kingmaker, and even having seen 4 level ups, I don’t think they’ve been noticeably more interesting than 5e, and this is quite similar to the Pillars of Eternity games (I never played 3.5e or Pathfinder tabletop, but I’m pretty sure I understand the lineage there). Plenty of level ups are just putting points into a handful of those skills that, at least in CRPG form, don’t really manifest in interesting gameplay the way they do in Larian’s engine, or even the passive checks that happen in Solasta.

As I see it, 5e’s main advantage is speeding up the math, which matters a lot more when you’re calculating it by hand. The main thing I prefer about it other than that is that it’s a flatter character progression. Using Pathfinder: Kingmaker as an example, a single level up’s worth of to-hit and armor class turned a Bear-Like Ent from “nearly impossible” to “trivially easy”, and I saw the same phenomenon play out plenty of times in Pillars as well. In 5e, you do get more powerful, but not by orders of magnitude like those 3.5-based systems, which makes any given encounter feel more tactical rather than feeling like you should have just gained a level to trivialize it.