Crimping vs. Soldering

[My5ABaby]

Throughout the years I've made various electrical connections (who with a 7 hasn't), but have never really known what I was doing other than some brief instructions from friends.

So my question is, what's the right way to connect two wires together?

I've read on the soldering vs. crimping debate and am leaning towards crimping being the proper way to connect two wires. However, I am finding all kinds of mixed results as to what kind of connectors to use, what kind of crimpers crimpers, insulated vs. non-insulated, etc. I've also ran across Posi-Tite connectors that seem quite interesting.

Maybe some scenarios will help.

I'm installing a new sensor in the engine bay and need to make a connection in the engine bay.

A second 12v outlet in the cabin. I have one wire running off an existing positive connection and one coming from the new outlet. How should I connect those two?

Installing a new EMS system. What kind of connections should I use there?

I prefer to leave everything so it's easily replaceable so not using a butt style connector is a preference. Although it would be good info to know the very best method, a budget method would also be good. I can't afford $400 crimpers and connectors that cost $20 each.