What diff locker is best

All I've had have been OEM cone or clutch types in 8-3/4s. Good enough for me back in the day. Good enough for me now.
My buddy on the other hand has had a Gleason Torsen in the Dana 60 in his '70 440 4spd Cuda for 30 years. It's very similar to the Trutrac, and he loves it. It was intended for a Ford truck, so he had to get custom axles, but it's been great piece for a long time.