Although I'm not a med student (yet, hopefully) so I don't know what the experience is like there, I've worked in clinical research for the past three years through two different medical schools. The first was in an outpatient clinic, the second is in an ED/Trauma center. I'm also involved in undergrad 'wet-lab' type research with one of my professors. Both have their benefits.
A day in the lab encompasses eyes eternally glued to a microscope and fingers permanently stained blue from unending amounts of hematoxylin. A day in the ED means dealing with cranky nurses, patients who really don't want to answer my questions (which, frankly, I can't blame them for ... even
I wouldn't want to answer the survey questions), and a pager that just loves to go off during my lunch break.
I love clinical research because it's really educational and a great experience; talking to patients and staff and working in the unit had been invaluable to me in deciding to go into medicine. Also, I think it's easier to see the impact that your work has on
actual people. The first clinical research job I had dealt with tobacco cessation, the work I did with people there is one of the most rewarding things I've ever done.
That said, I love lab research because it's more varied, I get to do bench work, lit searches, write papers, etc., etc.... And at my level, there is also more active involvement and opportunity to do my own little side projects (as opposed to clinical research which is much more regimented due to the constrain of IRB approval). I also love the feeling I get where the research we're doing is a giant puzzle that we're slowly picking away at.
From my experiences, the skills I've gained through CR have been much more 'soft skill-based' (i.e. people skills, communication, leadership, etc.), where as everyday in the lab is a reinforcement of the good old scientific method. In addition, of course, to the skills that come with being alone in the lab a midnight with your lab partner just having spilled XYZ chemical going, "****, what do we do, what do we do!!!!" Good times...
For me, both are rewarding, but in the end I guess it really depends on what type of person you are and what you enjoy doing.