I enjoy using Wago lever lock connectors. They are infinitely better than suitcase connectors or wire nuts and less hassle to install than crimps. They are worth the extra costs hands down and are reusable! They also are good at joining varying sizes of wire (in this case AWG sizes 28 to 12 which is just perfect for our trains).
Here is are two assortments - one is the 222 style, the other 221 (40% smaller footprint):
https://www.amazon.com/Wago-22...rtment/dp/B01GVTVY12
https://www.amazon.com/Wago-22...018MGMFDI/ref=sr_1_3
Just be sure to get real Wago ones and not the off brand knock-off lever nuts as the knockoffs do not meet UL or other safety standards and are of inconsistent quality. That is not to say that one may not find that certain knockoffs are just fine for this low voltage purpose, but I can't justify taking the chance after getting burned.