I, myself, has personally used both platforms on my laptop (A hp and macbook), and, overall, my desktop (Windows-based which is even older at 8-9yearold) hadn't been hit by a virus which as I take precaution of ignoring totally dubious emails of links, files, etc, even from my friends, even to the point of totally locked myself out from running even legitimate website's scripts and ads (even MS and Apple's own website I've gotten problems viewing due to me disabling scripts).
Thus, if you have a particular budget and certain softwares that you have to use which is available on that platform, you should go ahead. Both sides has its pros and cons, design-wise, usability-wise.
Anyway, safer on Mac, probably, except my uncle who uses only Mac, got hit by virus, even though all his stuffs were gotten from Apple Store from hardware to software and the only thing he does was video editing recorded on his video cam.
Thus, practice caution and you'll be just fine.