GitLab pretty much covers BitBucket (code), most of Bamboo (GitLab CI), maybe Jira if you use it only as a basic issue manager (forget about Agile stuff).
Confluence is probably the hardest one. You could use any wiki software but the new "live-editing" stuff (Google Docs style) is pretty good for productivity. Hard to find an on-prem equivalent. Confluence's integration with Jira is hard to compare too.
What agile stuff are you missing from the paid versions of GitLab? We have epics, roadmaps, milestones, and iterations. The only thing that is missing I can think of is workflow enforcement, but that doesn’t strike me as Agile.
Last time I checked I could not modify the fields of an issue (e.g. introduce a random drop-down or a checkbox). Here Jira and TFS were always excellent.
I always go the impression that GitLab was doing excellent in code related workloads but sub-par in issue and test record tracking.
I really wish MedisWiki was in a state that it could be rolled out as a replacement for Confluence. And in a lot of ways it can be. But sadly a lot of companies go the other way.
If you likes gitlab and look for better planning capabilities you can have a look at Tuleap [1].
Tuleap shines with very advanced tracking capabilities and, most important, empower end users to manage it. Unlike Jira, you don't depend on a central admin to tweak you configuration, everything is at hand.
Git & CI capabilities are built-in but if you prefer gitlab for that, you will have soon an integration between the 2 tools. It's part of the next delivery [2] due mid november.
Most of the places I know of or where friend's work use Atlassian. I am wondering if this will drive a shift towards GitLab considering the general consensus I've heard is that GitHub Enterprise is too expensive.
Confluence is probably the hardest one. You could use any wiki software but the new "live-editing" stuff (Google Docs style) is pretty good for productivity. Hard to find an on-prem equivalent. Confluence's integration with Jira is hard to compare too.