[Philip Lelyveld comment: I'm not sure if this is scientific or just marketing for their clients. But it does provide useful info about their focii and rates.]
The following companies are listed in the 2017 Virtual Reality & Augmented Reality Developers Leaders Matrix:
NEXT/NOW™, hedgehog lab, Program-Ace, NotionTheory, Fishermen Labs, Corporation Pop, Gramercy Tech, Live Typing, VEAR EXPERIENCE, Blue Label Labs, BidOn Games Studio, Sutter Group, Eden Agency, Hyperflow Labs, and Mindgrub.
In Clutch's research process, analysts evaluate many quantitative and qualitative factors. These featured companies have been distinguished based on industry recognition, market presence, and ability to deliver results to clients, proven by in-depth interviews with current and past clients. This comprehensive approach is designed to give buyers an honest and thorough understanding of what the service providers can do and how they perform throughout the project.
See the full story here: https://clutch.co/developers/virtual-reality/leaders-matrix