What sold me on NetBSD is the wireless drivers being easier to access, this forum (everyone on here is great), appears to be a smaller community, and a lot of the development around NetBSD. What turned me on, on the development side is pkgsrc and some lectures I watched on youtube. Most notably, a lecture from Andrew Tanenbaum (probably has written the bible of OS design and implementation) on OS design research using NetBSD. From what I gather, NetBSD is the place to be to experiment with OS design. Rather it is actually implementing new designs/ideas or borrowing bits and pieces. It comes across as the BSD most willing to try new stuff. An example is Minix porting over NetBSD userland tools and there are several scholars in research design and implementation that reference work on or with NetBSD. Operating system programming has personally always interested me and something I definitely want to get into. In this regard, NetBSD wins me over on the those technical merits, but I also hold different values on what I find valuable than someone else might. While OpenBSD is easy to get going, they are not afraid to throw out old code, which isnt a bad thing, but as I've read, its been known to mess up configuration files. For me, I like a set something up the way I like it and forget it and get to work. Its why I still use XFCE as I have for the past 12 or so years since the transitition of GNOME2 to GNOME3. I also like the relative ease of compiling the system, which I just started playing with. The build.sh script is nice.
Also on technical merits. I read somewhere awhile back that NetBSD does stick more closely to a lot of the original ideals of BSD 4.2 also. This I can't confirm or deny.
The great thing, like mentioned above, each BSD definitely exists to fit niches of users. At the end of the day, it is all about ending up with a system and set-up your happy with. If it is NetBSD, then it is NetBSD. If it is OpenBSD or FreeBSD, then it is that. If it is OpenIndiana or Haiku or some obscure OS I've never heard of, great! Keep using what you like and what you feel fits you and your use cases.