What's your opinion?
Should I invest time learning UWP+C# or WPF+C#?
The your question is related to Entity Framework. Some time ago I read that EF 7 was going to replace EF 6, now I was searching for EF 7, and appears that EF 7 is still in RC1 and never passed that... Microsoft gave up on that one? What is the best option (for now and future) to DB access that I could use with WPF or UWP (preference for support with SQL, SQLite, and other formats)?
Certainly in my area, there is far more WPF development than UWP. I think that is likely to be the case for some time because there's way more functionality in WPF.
Entity Framework is very popular and a good choice to learn for commercial employment.
All in all WPF and EF are a good choice if you're talking desktop development.
It has to be said that there are more employment opportunities for web developers nowadays though.
There are probably some cold hard stats could back this up but you just need to look at job ads if in doubt.