An "off-grid" version of Windows 7 that can be used forever inside other OSes
Background:
A year ago, I switched to Android (from iPhone). I have very high productivity needs, and don't do social media. I installed all the apps I needed, and then switched off all updates.
The result? Life changing.
Pros: My phone behaves predictably. The UI never changes. My friends and colleagues keep complaining about how after updating this or that app the buttons changed, or free features became "paid-only", or the phone slowed down, or the app keeps crashing. Not for me. Everything works exactly as it used to a year ago.