Solder and heat shrink for splices, but for anything that requires connections ie: spade lugs, ring terminals etc, I use only the heat shrink crimp type. I've found those much more reliable than a plain crimp terminal. I just got some heat shrink crimp terminals with solder inside, can't wait to try those out.
I do like those posi lock connectors when I need to repair something on the road. Always keep a few in the glove compartment.