Full Moon clips are the fastest re-load by a wide margin. They are best with the 45 ACP cartridge loaded with FMJ Ball. The larger chamber mouths and stubby cartridges make for the fastest reload possible with a revolver in my experience and observation.
I like the full moon clips for the .45 revolvers I've shot (but no longer have).
I tried spring loaded speed loaders in my .38 and did not like them. My setup for the competition was not correct for spring loaded and I had rounds falling all over the place. I prefer the "twist to load" kind.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)