"Then there’s the difference in licensing that Linux and the BSD family
use. While both use open source licenses, Linux uses the GPL which favors
users by forcing developers to release any of their modifications to
GPL-licensed software as open source and with the same license.
The BSD family uses the BSD license, which favors developers by allowing them
to take open source software, make modifications to it, and then keep it
proprietary if they wish rather than forcing them to release their changes as
open source (although they still could if they wanted)."
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Source: http://www.makeuseof.com/tag/linux-vs-bsd-which-should-you-use/
In other words, choosing BSD is going for more security indeed (no expert,
but it sounds like overkill).
But that can be argued:
https://en.wikipedia.org/wiki/OpenBSD_security_features
The GNU C library didn't include these functions because to them it leads to
other errors.
So BSD is much less flexible, probably even more secure (but that sounds like
overkill), but certainly not privacy friendly since you're at the mercy of
the developer's whim.
Also I doubt Microsoft will change their ways by 2020. And they don't give a
damn about your privacy. As for security, it's not as good as GNU/Linux,
period.
Following your reasoning (you want more security and privacy), you don't make
much sense in your choices.
But you're free to leave Trisquel if you want.