If you want the best technical solution at the moment with the most expansion options, get the Vive. Be warned it will get eye-wateringly expensive the more you bolt onto it (deluxe headstrap will be another £90-£100, wireless will be at least £250 when released, additional tracker pucks will be £100 a pop etc etc...you get the idea). Semi-modular design, good for most glasses-wearers.
The Rift is also excellent, and a significantly cheaper option if you only have a small play area or intend to play mostly seated games. If you go for a full three-sensor room scale solution, you'll need a crapton of USB ports and cables and a hub capable of handling it all. Controllers are better ergonomically for certain games. Larger library of high-quality content, although that's now being eroded as the same titles become available natively on Steam. Not so good for most glasses-wearers.
LG are intending to release a SteamVR headset similar to the Vive (but slightly upgraded specs) sometime in the future, no release date as yet, so most likely 2018/2019. HTC have hinted at a new Vive revision sometime in 2018. Facebook have said they won't be updating the Rift for at least two years.
That's pretty much sums up the state of high-end PC VR options as I currently see it.
Edit: I should also mention the cheap Microsoft partner options, but they're still unreleased and unproven in terms of high-end VR gaming. Personally I'm suspicious of how well the tracking will work on it, the controllers, and whether the higher-resolution LCD displays will hold up to fast motion.