I guess different environments lead to different flows being better but managing code reviews via email sound really horrible to me. There is no good way to track who has actually reviewed the code, no easy way to annotate the code, and no easy way to give the code a seal of approval. Both Bitbucket and github provide good methods that are easily tracked for this. It' one thing to send an email saying please look at this code but It's much more difficult to track who on that email has done the review and who approves the code.

We use feature branches and issue pull requests/code reviews from those feature branches in BitBucket and it's been a universally well received tool and definitely increased the quality of our code reviews and overall code base.

I really like having code review persisted right there in the repository. I often go back and look at discussions on old pull requests to figure out why we decided to do something one way or another. It's even "higher resolution" than commit messages (which should also be good).