>>410846982
Quest 2: Much higher resolution than index, you will need to buy a third-party head strap as stock is garbage. With a thin interface FOV is fine.
Pico4: Pancake lenses, better displays, proper IPD adjustment, and a good stock headstrap. Great FOV and form factor, but their pancake lenses have their own type of annoying "lens flares" you may hate. Useless for anything but streaming PCVR.

In either case you're looking at streaming VR instead of having a PC-native experience, but with recent improvements to Virtual Desktop it barely matters.
If you're looking to get into social VR with FBT the index is still a good package deal, since you get the basestations and the finger-tracking Index controllers, but using a quest 2 + index controllers is becoming a more common preferred setup.