I strongly prefer GitHub's flow to Gerrit or Phabriactor. Those tools have far too much complexity; I find the new GitHub stuff to strike a nice balance.

I haven't used Gerrit in a few years though, maybe it's changed.

What I miss at github is a single view that list all the commits in a pull request, in sequence, with both commit messages and diff contents, with possibility to comment both message and diff. Oh, and have the commits show in the actual order the commits will show up in the history.

Github has certainly come far this last year, but these are all oh so simple and basic stuff.

Phabricator is shit from my experience but only used it with svn backend. Gerrit's main downside for me personally is that the web interface captures bowsers search function. While it's nice, I don't like my 'os' level functionality to be overwritten.