Clinical research is much easier for papers, abstracts, posters, whatever. Mostly because a lot of the data is already there and all you have to do is 1) think up a good question and 2) analyze the data. With basic science, the hardest part is step 0: getting your experiments to work. But if you're talking about getting a New England Journal article as a med student, then I'd say that's just as hard as a basic science paper (if you can even do it at all). That's because NEJM typically publishes either very interesting and relevant case reports or really big clinical trials that the PhDs and epidemiologists have priority over.
But if you're content having papers in the smaller field-specific journals, then clinical research is much faster than basic research.