Github Projects is my preferred tool of choice. You have have repo-level as well as organizational-level Kanban-style boards, it has a nice integration with Github Issues and basically eliminates the need for yet-another-tracking-tool. If you need slightly more features, Zenhub is a nice way to use Github -- though I liked Zenhub, Github projects does what we need.
Our team size is 5, so I can't speak for what's useful for larger organizations, at least not from recent experience. However, Github Projects might not please the micromanager -- you can't lock down permissions to prevent those pesky developers from moving their own cards across the board like you can with Jira.
Jira seems to be a continuing hit with the micromanager-type PMs that busy themselves with robust reporting and tracking minutes while, in my experience, Github Projects (or Zenhub) seem to be popular with teams that just want to move quickly with minimal manager overhead.
So my vote goes to Github Projects, with an honorable mention for Zenhub as it has some features that some might find useful (like estimations and epics.)
I'd rather choke on a chicken bone than be forced to use Jira (or any of that suite of products) again. Obviously, I'm biased towards lighter-weight tools with fewer "features," so opinions will vary.