Choosing the right contacts is not always easy, especially if you do not have engineers specialised in interconnect designs. The quick answer to the question is: neither. One will be more suitable in some cases, while in other cases it will not.
Scenario 1: when you don’t have a choice. Probably the easiest case, in many situations you won’t need to choose because the choice will be imposed. This relates to aerospace and defence standards where most of the time contacts need to be crimped. Examples include the MIL-DTL-38999. This military standard indicates right in the title that the connectors must have removable crimp contacts.
Standards may often determine what type of contact you need, and it is likely that if you are in that situation, you already know what contacts and connectors you need.
Scenario 2: When you do have a choice. Solder contacts have little solder buckets at the back. They are usually preloaded in the connectors. Here is where it gets more interesting; if you do have a choice, that means you will need to pick the type of contact termination that is most suitable for your application. Souriau’s technical support team compares different advantages and disadvantages for both options, as well as screw terminal connectors that are available for certain product ranges.
Crimping is usually preferred for its high reliability especially in harsh environments. Soldered contacts are more vulnerable to corrosion and less flexible when it comes to vibration and flexing. Crimping can also be automated in a very efficient way if one has crimping machines into which the contacts are fed. However, the setup is costly.
For harsh applications requiring smaller volumes, soldering offers a more flexible approach, although it is less convenient to industrialise the process.