Ask HN: At a crossroads between *NIX and Windows ecosystems

This is not a troll or flamebait, but a genuine question. One I've battled with for a couple of years.

I'm at a crossroads between *NIX and Windows ecosystems. I've been heavily involved in both for the last 15 years and have extensive experience both with administration and software development on each (c/Python/perl, c++/c# respectively). I'd say I was equally well versed.

Unfortunately I'm now getting too old to constantly keep up with the industry churn. I have a medium sized family which needs attention and I also have a couple of product ideas I want to get out of the door in the next year or so.

I want to focus my efforts on one platform for both career and product development just so I have time to focus on what is important.

I've considered the usual facets such as cost, barriers to entry, salary, knowledge, supportability etc and have come up with no distinct solution either way.

Are there any views, trends or ideas that I am missing which will support either case?