I like to use these type splices when you have to make a quick splice for stranded wire.
McMaster-Carr

I prefer soldering and shrink wrap for permanent splices. Add a dab of silicone on the ends of the shrink tube and you have a splice that is coolant proof.

If you have quite a few splices inside a control cabinet though, din rail mounted junctions are probably the neatest way to do it.

It all depends on the speed of the job for me. I have been guilty of the twist tape splices in the past, but found they fail easily.