Talking of magazine loaders, I have an Uplula universal loader and two Speedbeez loaders, one for my Sig P365 and another for my recently acquired P320. I am new to shooting semiautos, and learned only recently about these mag loaders.
What I found was that at the range when I place the mag on a table, counter or barrel, put the Uplula on top of it, and load ammo, it aggravates the arthritis in my hands. I think this is because I am pretty tall, and the position of the mag on a low surface places my hands at an uncomfortable angle.
The Speedbeez loader works differently: The mag locks into the loader — you need a loader for each specific gun — and there is a scissor-like action one uses to insert the ammo. You don't need to rest the mag on anything, so you can hold it wherever it feels comfortable to you.
I think the Uplula is probably faster if you have a place to rest it and the magazine on. But I find the Speedbeez loader more comfortable.
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As for revolver speedloaders, I like HKS. I tried some Safariland speedloaders, but could not make them work properly and returned them.