These types of taps are not very good for a couple of reasons they only make contact with about 1/3 of the strands in the wire, and the connection is not tight so eventually they loose connection due to moving or getting hot and melting. Also a lot of time they cut several strands of wire which lessen the amperage load they can carry. Aaaaaand they look bad.
If done correctly soldering thoroughly connects all the strands in the wire, and the strip twist method if done properly will as well. and no chance of either one coming loose or melting.
But Splices are not as bad, but definitely a weak point in a wire splice. no matter how good you put them on they can be pulled out, and they are not sealed so the wire is susceptible to corrosion. If one were wanting to avoid a solder gun, the third best solution is probably to get un-insulated butt splices and use heat shrink on them.
They even make these to adapt to different sized wires