I've used GitLab in previous startup, I've had great experience managing multiple teams and multiple projects through it.
It's label-based organization which enables you to have multiple processes around same issues.
It also has built-in ticketing system for support and incident tickets. Communication with clients is native, you write a comment they receive an email.
Overall it had everything we needed in one tool 😄
I love Trello, but right now we are currently using a management software called Shortcut (app.shortcut.com). I actually really like Shortcut as well as it gets the job done and also integrates very well with Slack.
Haven't used Jetbrains, but to me, Jira and Trello are in completely different categories and do not compete at all.
Trello is awesome for individuals and really small teams that want to run fast, but I haven't heard of any teams over 5 that actually use it for sprint MGMT. It's just missing too many things.
Collabwriting