There are probably similar reasons for why I like both so much.
I like the consistent trigger pull of a SA gun. They are both thin guns which makes them great for IWB carry. I prefer to ride the safety with my shooting thumb and that means a frame mounted safety that fires in the down position. I like all metal guns. I love the ergonomics and handling of both (but especially the hi power). Of course, it helps that I shoot both pretty well.
One other thing I find appealing with them, is the wide variation. You can change mainspring housings, grip and frame safeties, triggers, springs, hammers, slide stops, and grips all fairly easily and with a wide selection for all of these components and completely change the fee of the gun. Though mine are still stock, I imagine I'll tinker with them at some point. It's one of the reasons I picked the 10/22 when I got my last rimfire rifle. I can start with the base gun and have change into a dozen different configurations over the years.