it depends on whether or not you can PROPERLY solder. technically you should actually use solder crimp-connectors for added security, with heat shrink tubing. but if you are mediocre or less at soldering then use quality crimp connectors and heat shrink.
soldering can make the wire brittle, leading to cracks and breakage. this is why a solder connector is a good idea, it contains the brittle section in a solid tube. but most people extend the solder past the tube, negating the advantage.
but solder connections have much less resistance as the electrons can flow straight through, whereas a crimp connector only has a small flow path. typically along the connector walls.