Both of the connection methods you have shown are only suitable for use where they are accessible for inspection. The bottom item is only suitable for use indoors.
I haven't come across a good soloution for joining cables inside a solid wall. Crimped connections don't need to be accessible but I hesitate to suggest them to a DIYer because cheap tools can easilly result in unreliable connections. All the maintinance free junction boxes seem to be designed to be installed in hollow walls/floors not solid ones.
Is there no way you can locate the joint somewhere accessible?