Crimp as best you can, then solder.

Must agree with @Tonyr1084

Soldering can lead to wicking up under the insulation, which can put stress on the joint.

I've personally seen wires fracture inside the insulation. Also seen flux get under the insulation and corrode the wires. I'd recommend staying away from soldering crimp terminals. A solder terminal is made to be soldered. A crimp terminal is not meant to be soldered, mashed with pliers or smashed with a hammer. The right tool for the job. That's not a soldering iron.

 

I've had to replace crimp terminals done by a contract manufacturer that specializes in cables and harnesses, because they weren't crimped correctly. Most hobbyists have worse quality tools and less experience. Strain relief can be improved with heat shrink tubing, or by tying the wires down.

 

Of COURSE! soldering must be done properly, and it is very obvious that a whole lot of folks have neither the right tools nor a clue as to how soldering is done correctly. But those folks also do not have the correct crimp tool nor a clue about crimping.

 

I've had to replace crimp terminals done by a contract manufacturer that specializes in cables and harnesses, because they weren't crimped correctly.

Boy is this true. I've seen companies crimping wires WAY over crimped. This results in wires that can be pulled out more easily. Having MANY years experience in electronics manufacturing I've seen this from time to time. I've seen the opposite more frequently. An improperly set up crimper fails to make a secure crimp. One job I was inspecting portable defibrillators. Being new there they didn't want to let me near the job because of the nature of the tool. With several inspectors out I was asked to "have a look". What I saw raised tremendous alarms in my head. Crimps easily pulled out, so easily they could come out just from vibration. Took this information to the QM (quality manager) and explained how I was certain the person(s) doing the crimping were not setting the tool up correctly. They also had a lot of crimps with wire insulation trapped inside the crimp barrel. Shortly after that I was giving lessons from IPC 610 A, back when 610 covered crimps as well as soldering. Later crimps came out as their own spec; 620.

Of COURSE! soldering must be done properly, and it is very obvious that a whole lot of folks have neither the right tools nor a clue as to how soldering is done correctly.

I don't know this to be quite so obvious. Sure, people don't have temperature controlled irons, but neither did I for 30 years. Still, I've managed to make some darned nice solder joints. And with the Temp Control'd irons I've managed to get wicking up under insulation from time to time. Wicking is hard to control. Unless you put a heat sink clip on the wires it's easy to get wicking. As for having no "clue as to how soldering is done correctly", my first experiences were with a Weller soldering gun. Big thing as I remember. Or maybe it just looked big to a 7 year old boy. That's when I first started soldering. And it looked horrid. But when I learned about flux core rosin solder, things improved quite a bit. Wiring speakers with wires soldered to the terminals, by 10 years old I was doing some pretty good solder work. But also had wicking issues. To this day I still get a little wicking from time to time.

Soldering takes time to learn. But the old adage, practice makes perfect.