There is a 3rd alternative...
Atolia, the one and only workspace your team needs
Atolia is a power-packed all-in-one digital workplace: Chat, Video calls, Tasks & Projects, Calendars, Documents, Notes...
Accelerate your team's collaboration game.
Implement it in minutes and save money. Atolia is cheaper than most of the business instant messaging apps.
Why choose Bitrix24 or Rocket.Chat?
Bitrix24 offers roles management, contact management, chat, file sharing, mentions, polls, groups/channels, 1-1 and group video calls, recording, online document editing, task management, and help resources. On the other hand, Rocket.Chat offers user activity, chat, file sharing, mentions, voice messages, groups/channels, gif and emoji, threads, screen sharing, user profile, newsfeed, "do not disturb" mode, mobile, web and desktop apps, integrations and API, on-premise solution, SAML/SSO authentication, end-to-end encryption, and two-factor authentication. However, Rocket.Chat does not offer an entry level price, custom domain name, breakout rooms, participant permissions, subtitles & translations, documents management, or training resources.