Recs.
Updated
All-in-one voice and text chat for gamers that’s free, secure, and works on both your desktop and phone. Stop paying for TeamSpeak servers and hassling with Skype.
SpecsUpdate
Pros
Pro Friendly payment policy
Free account have no tangible restrictions.
Premium account is just a way to say "thank you" to developers. And it work for all servers of discord (not as in slack). And it can be purchased by one who wants. In contrast to Slask, where all active members of the server should be "premium".
Pro Does not allow NSFW related things to be posted unless in a NSFW channel
Cons
Con Developer's previous company was sued for privacy violations, among other things
See:
http://classactionlawsuitsinthenews.com/class-action-lawsuit-complaints/openfeint-green-international-privacy-class-action-lawsuit-complaint/
https://www.ftc.gov/enforcement/cases-proceedings/closing-letters/openfeint-inc
Discord's privacy policy also states that while they might not sell your data, a company they get sold to will quite possibly attain said data and thus may be in "more" shady hands.
Recommendations
Comments
Out of Date Pros + Cons
Con Not a generic "team chat" tool
All the UI and the features are aimed specifically at communicating with your gaming team/clan.