[codeapprove]

That's a shame, heard only good things about those tools.

Shameless but timely plug: I'm building a much better code review tool for teams on GitHub. Check out https://codeapprove.com and if you're interested to hear more just email me (sam at habosa dot com).

[lima]

Reviewable is another similar review improvement tool for GitHub: https://reviewable.io

...or just use Gerrit[1], which can do everything these do out of the box, and has a much nicer workflow than GitHub once you got over the learning curve.

[1]: https://www.gerritcodereview.com

[Macha]

I've never actually used Gerrit personally, but I've twice been on teams that had recently dropped Gerrit at the time I joined (once for Bitbucket/Stash, once for Github Enterprise), and neither seemed to ever look back.