Skype for business. Because I need a VM to have it running on linux. The quality is even worst than the skype for individuals. The web client is useless (no video, no audio. based on User-Agent) Their is no fallback on phone. The android client won't connect you if you didn't give your phone number. By default you can't see your full company directory in your contact

You can apply most of this to office365. Excluding that the web clients are not that bad (if you forget about live edit, and phone client) Outlook too. filtering your mail without telling you. Creating folder without your agreement