What can we improve about GitLab? It seems to fit your requirements. It has issue tracking and task assignments. If you want an idea board please consider using something from https://about.gitlab.com/applications/#scrum-boards
To be perfectly honest, we are more than happy with GitLab, we just switched from BitBucket, and so far have not been disappointed. Though the only comment my colleague pointed out about, very minor of course, is how he would love to have review board integrated with GitLab somehow where we wouldn't have to self host it. I was only looking for guidance and hence posted on Ask HN, again so far very happy. Thanks.