I used 16 gauge. It fit fine into the .187 disconnects I got, but was a bit big for crimping Molex pins. I still got the Molex crimped on, and so far they've held up through several plugs and unplugs, but I am carefully adhering to the "don't pull on the wires, pull on the plug" rule.
Otherwise the 16 gauge was fine. If that's what you have, go for it.