I'm happy with the ones I bought from Home Depot on a whim. They need a very small screwdriver, but they hold the wire tightly, and work with my huge double 14 gauge wires. I'm not as happy with the ones I got from Blue Jeans; I probably just don't have the hang of it, but it seems that the wire slips out easily.

I am the Doctor, and THIS... is my SPOON!