I don't think any of what I said is specialty specific. I'm working on three projects right now that are all surgical and all are some form of retrospective chart review and database analysis (as an aside, working on three projects at the same time is generally a bad idea, I regret doing it but didn't realize things were going to stack up like this until it was too late to drop any of them without feeling irresponsible).
There are cool opportunities to do basic science type stuff involving animal surgery, but I don't think these are necessarily the safest bet for medical students depending on the amount of time you have. I have friends doing projects like this and while, yeah, it's sweet that they show up to work in scrubs and get to "operate", at the end of the day they still have the same limitations as other basic science projects: longer timelines, rougher learning curve, higher probability of failure/necessary troubleshooting, and harder for you as a med student to really be in charge on your own (obviously this is variable, but generally you're depending on a lot more on manpower and help from others in a basic science context than you would be as a data jockey doing a clinical project).
I am also planning to take a year off and haven't decided if it will be basic or clinical research, but I'm leaning towards clinical for all the reasons above. If I really enjoyed basic I'd do that (obviously you should do what makes you happy), but since I don't feel strongly about it I think I can be more productive in a clinical research setting with that time.
Lastly, I'll be the first to say that I'm far from an expert on any of this, so take what I say with a grain of salt. I'm just a rising M2; a lot of what I say is mostly informed by talking with my research mentors, who have a lot of experience helping med students get involved in productive projects that help them match to great places. Basically they've told me to be pretty merciless when choosing projects. If you're not very confident you can get something to publish out of it, don't do it. You're not a premed doing research to understand the scientific method, you're at a stage in your career where your time is limited and you need to focus on investing it in things that will allow you to show some sort of track record of productivity (abstracts/presentations/publications).