Linux

It was more than a few years ago when I switched my desktop systems from Windows XP to Linux. I was already familiar with the new environment (having already used various unixes for years) so the transition was mostly a matter of replacing my favorite apps and wrangling Wine into running my games. Both those tasks are pretty easy these days.

More importantly, Microsoft's adware, spyware, and hardware demands at that time were nothing compared to now. If I were to make the switch today, I imagine it would be not just a breath of fresh air, but more like being instantly cured of debilitating asthma. What a relief.

To people planning to switch with no prior experience: Please be patient. Like moving to a foreign country with different language and culture, it will be awkward and possibly frustrating at first. You will master it over time, though, and end up with control of your computer and data again. Well worth the investment, IMHO.