Valve Index user here too! So far, there’s nothing out now that interests me enough to upgrade yet. I’m really hoping something comes out soon because I’d certainly like some more resolution - but I’m not willing to give up the FOV or the large sweet spot the Index has. I have my SteamVR super sampling set to 150% and also run the OXR Toolkit with FSR sharpening set to 80, while also using DLSS, and the image quality is pretty darn good IMO. Displays are mostly readable, though not tack sharp like they are when I use TAA - but the extra overhead lets me run my FPS at 40 or even 45. I do have a 3080 however.
I would like whatever headset I replace the Index with to have:
Similar or slightly higher FOV
Higher resolution
Eye tracking / foveated rendering