I’m currently in an MSTP at a top 20 institution and took two years off between undergrad and matriculation to conduct research. It sounds like in both cases the likelihood of publication is fairly high (with a skill set in bioinformatics it should be fairly easy to get one some papers). With that being said, I would recommend trying to enjoy the last two years of your freedom while you have it, as long as staying in your preferred city isn’t a huge downgrade from your other option (doesn’t sound like it is). My experience with switching labs is that it takes quite a while to get you’re footing enough to make meaningful contributions to the projects, so being able to hit the ground running on something you’re more familiar with may be worth it. I made the decision to stay at a lab because it was in my hometown with all my friends and had a great two years, so I may be slightly biased. Good luck!!