I prefer hipchat to slack because (1) it has posts within a channel, which can essentially create a unique thread (slack will soon introduce threading), and (2) it allows you to associate different wunderlists to each channel. However, the mobile app is weak. Slack has you so beat here, get your act together. Mimic your desktop experience rather than giving us this stripped down app that took a Jr. Developer one weekend to write.
dgsinclair about HipChat – Group chat for teams, v3.13.1