(XT30/60/90) Have discounted these as they're not latching.
Amass makes latching versions....

but even the standard unlatched type fit together very snugly, after all they are used in relatively high vibration models etc. I use XT60 for test leads, love the things, XT60-banana, XT60-alligator, XT60-testhook, XT60-wire, XT60-2xXT60 (parallel), XT60-XT60-XT60 (series), XT60-USB, XT60-Barrel, XT60M-XT60M, XT60F-XT60F.... and so on, so I can just plug together the ends to make up the right cable as needed. The connectors are even marked with a small embossed +/- so you can always be sure you're following the same "standard".