What is the best team chat software?

Some parts taken from their Privacy Policy,
«Information we collect may include but not be limited to username, email address, and any messages, images, transient VOIP data (to enable communication delivery only) or other content you send via the chat feature.»

« [...] we may conduct research on our customer demographics, interests and behavior based on the information collected. This research may be compiled and analyzed on an aggregate basis, and we may share this aggregate data with our affiliates, agents and business partners. [...]»

Also,
«You may give us permission to collect your information in other services. For example, you may connect a social networking service ("SNS") such as Facebook or Twitter to your Discord account. When you do this, it allows us to obtain information from those accounts (for example, your friends or contacts).»

«As we develop our business, we might sell or buy businesses or assets. In the event of a corporate sale, merger, reorganization, bankruptcy, dissolution or similar event, your information may be part of the transferred assets.»

and in their Terms of Service,
«By uploading, distributing, transmitting or otherwise using Your Content with the Service, you grant to us a perpetual, nonexclusive, transferable, royalty-free, sublicensable, and worldwide license to use, host, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, perform, and display Your Content in connection with operating and providing the Service.»

At the date of 20170906 ( https://discordapp.com/privacy https://discordapp.com/terms ).

In other terms, this protect them to operate any business based on user's data. For example selling detailed stats and profiles to advertising partners or other data mining companies. This do actually makes a lot of money, even more they're invested in lobbying the use of their service.