I wouldn't say these two are in opposition; while CodeBrag doesn't have support for pull request, I don't see why it shouldn't in the future.
It would be perfectly valid to use CB to review commits in the branch for which the PR is done, and then come back to it once more commits (with fixes) are added.
Also, using PR is only one style of work, and I don't think it's the "only right choice". Code reviews of code as it is written, that is during development of a feature, can help you to spot any problems faster. Waiting until a PR is done can result in a long feedback cycle.
You can use CB to track a specific branch that either your colleague is working on, or maybe you are working together.
It would be perfectly valid to use CB to review commits in the branch for which the PR is done, and then come back to it once more commits (with fixes) are added.
Also, using PR is only one style of work, and I don't think it's the "only right choice". Code reviews of code as it is written, that is during development of a feature, can help you to spot any problems faster. Waiting until a PR is done can result in a long feedback cycle.
You can use CB to track a specific branch that either your colleague is working on, or maybe you are working together.