What tool(s) do you have?
> Buy better crimp tools
This is most likely your better path forward (as even if you go with pre-crimped, unless you can get all custom wires pre-crimped on both ends you'll likely still need to make some crimped ends). And not only "crimp" tools, but also better wire stripping tools (as you do have to strip the wire before you crimp it). The better tools significantly reduce the time needed, and for 15+ crimps per unit, may make a world of difference overall.