I usually tap into it wires using your option 3. Done properly, this has worked for me for a lot of years without issue in a plethora of vehicles. The splice-type connectors, on the other hand, seem to invariably come loose and fail over time.
Besides, depending on where you are able to tap the VSS wire, soldering may or may not even be practical. I installed a NEX-8000 in an older CR-V recently where the only place to get at the VSS wire was in the PCM behind the glove box. I was able to access about 2 inches of the wire while upside down, looking up at it, and (basically) standing on my