Good luck with that now that Hollow Knight exists.
I have played both Hollow Knight and the first Ori, and HK is infinitely better in every single sense than Ori: gameplay, graphics, story, artstyle, soundtrack, sound effects, length, bosses, secrets, DLC, game design... everything.
HK is absolutely not better in every single way. It's more exploration heavy, in that it's less linear in terms of where you can explore (Instead of needing Item A to access Area A, you might be able to explore MUCH of Area A B C and D without item A, but then get stuck in each of them until you get the item that lets you advance, which is still pretty standard metroidvania, where Ori just stops you at the gate much of the time), and it has a focus on combat that Ori lacks, but Ori feels MUCH better to traverse around the environment and has fantastic tricks of movement that Hollow Knight largely doesn't rely on.
They're both the best current metroidvanias, and both are strong in different ways. Also, there's no fucking universe where HK has better graphics or OST. And the length is debatable. Hollow Knight is certainly longer, but I'm not sure that's a huge boon. It's slower to traverse, has more back tracking, and has a LOT of 'oh, I have to go all the way fucking over there?' moments. I think they're fine enough in that game, but Ori doesn't suffer from that at all. Compare: In HK if you die to a boss it might take you 5 or 10 minutes to get back, only to die again. In Ori you will have saved literally right before any challenging section, and it might take you a dozen tries to complete it, and you still did it faster than just 2 attempts at an HK boss. Of course it's shorter. Super Metroid is FAR shorter too but it's also damn near perfect.