What kind of wire is this?

[BravoXray]

Solder vs crimp. The best type of connection is the one you are the most proficient in.

I would say that it all depends on the application and operating environment.

 

[Topzide]

Use hot glue stick to coat the splice and the slide heat shrink over it. When heat applied, seals it up tight! This way I always have the right size heat shrink.

 

[ArlyA]

Glued heatshrink used with uninsulated crimps are my go to wire fixer.