>>301384235
Honestly the Index is better overall, but it's not $600 better. 
- Real world usability is mostly the same with the exception of tracking: Index uses base station tracking, whereas Rift S uses inside out. There's advantages and disadvantages to both. 
- They're both about the same for jumping in quickly but you may have more hoops to jump through for Rift S since you'll need to open Oculus then SteamVR. 
- Everyone says the Index is one of the most comfortable headsets but a few, myself included, don't like it that much - I preferred my Rift S more. 
- The Index knuckles sacrificed a lot for meme finger curl tracking, so ergonomically are not as good as the Touch 2's, let alone the Touch 1's on the CV1. The knuckles also need to be RMAd regularly because of the thumbstick drift issues.

As I said the Index isn't too comfortable for me and I can't get the max FOV out of it because of the shape of my eye sockets. That said, it reliably starts when I want to: I had major software issues with my Rift S to do with various crashing and having to restart my PC to get into VR. I feel like I'm a minority with that though. 
Both are good headsets, I'd lean towards saying the Rift S is better as a first VR headset.