I reckon that if I get into competition, Safariland might be better for winning timed gun games, but HKS won the sturdiness contest, for my peace of mind, during the 1984-1997 period I carried revolvers as duty handguns. Both of the reloading techniques I use, which is dependent on the frame size, secure the cylinder against turning, so the twisting necessary with the HKS loader is not a problem.
It does NOT require "two hands" to keep the cylinder from turning. One finger against the cylinder will secure it just fine.
There is another brand out there now, however, that may be better than either, the SL Variant loader. I may order a few soon, as I am likely to revert to revolvers after I retire from policin', and often carry revolvers on my own time.
My favorite speedloader, for now, however, when carrying an SP101, is those all-stainless steel speed loaders made by Ruger, a second and sometimes a third SP101, backed by Speed Strips.
Bianchi Speed Strips, which are handy for toting spare rounds, are NOT very speedy for a full reload, but are a VERY fast, sure way to get two rounds into the cylinder, and sometimes two quick, sure rounds might save one's life.