Equal weighting between personal experience interviews and case, until you know which one is your strongest

Once you do know which one you are strongest, focus on your weaknesses.

For example, if the case is what you need to focus on, start by forcing yourself into having MECE structures, then on depth of ideas. Once that is done, improving your communication skills is key, especially if interviewing online

Take your time, and do not stress out if your initial answers are not perfect. Getting ready for MBB interviews is about small progressive improvements, not big jumps in capability

If the interview is close, I'd prioritize structure, synthesis, math accuracy and your fit stories.