Ori + its sequel are not on the same level as HK, in my opinion. The combat in the original is really bad/way too easy, and the exploration is just okay. The sequel drastically improved the combat, but the map is significantly worse; it's essentially just a "hub and spoke" where you go to one of 4 (IIRC) separate disconnected areas, grab the powerup which does more or less nothing in the other areas, use it to finish the area and beat the boss, rinse and repeat until the finale.

That being said, they are still very good games; excellent atmosphere, artwork and presentation, some genuinely haunting, creepy, and awe-inspiring areas. But I think Hollow Knight is a tier above them.

> The combat in the original is really bad/way too easy, and the exploration is just okay

Personally I find combat to be one of the less important aspects of Metroidvanias. I prefer the main source of difficulty coming from platforming around environmental hazards.

I felt like exploration in Hollow Knight was a bit too broad, and lead to too much unnecessary backtracking. Backtracking is a balance. It's a staple of Metroidvanias, but if the backtracking search space is large enough and places aren't distinctive enough then the search for a previously insurmountable obstacle can start feeling like looking for a needle in a haystack. That was my experience in Hollow Knight, and something I felt like the first Ori game did better.