Multiple blades are the big draw for me, along with simplicity.
My favorite patterns are the stockman, Barlow, canoe, sunfish/elephant toe (not the smaller toenail), 4 blade scout/camp/demo/ engineers knife, two blade slipjoint folding hunter, and moose.
I do have some single blades (including friction folders) but they don't get carried as often. A single blade knife isn't as versatile as a multi blade. No one blade profile is "ideal" for every knife task.
I grew up (or aged, anyway) with slipjoints. I received my first knife in 1961 or 1962 at age 6 or 7. My Uncle Bob (U.S. Army; Infantry) was home on leave between Vietnam and Germany, his next duty station. He gave me his issue Camillus Demo Knife, issue Jet Pilot Survival Knife (I have less than zero idea why the Army issued him an Air Force knife. He was a grunt; not a pilot or Huey gun ship gunner.)
I have a few lockbacks (got my first Buck 110 in '67 or '68, which I carried daily for at least 10 years, when I replaced it with an Old Timer 7OT in '78. I carried a 110 or 7OT or 6OT pretty much every day from '67 or '68 until 2021. Sometimes when I went hunting, I replaced it with a Western L66 or Schrade Sharp Finger, or a Mora N°1. Truth to tell, I could have gotten on without the lockbacks, (again being honest) which I probably "abused" scraping head gaskets, and other engine parts, cutting tire valves at a tire repair, prying the tanks off radiators (after heating to melt the solder), cutting up to 8 guage wire and stripping 4 aught welding cable, coax cables, and such when I didn't feel like going back to the tool box for a scraper, side cutter, wire stripper, or whatever. (I used the screwdriver blade(s) on my scout knife or SAK, which I have carried every day since '61 or '62 and counting.
Haven't carried the same one the entire time, of course. My mum stole the two Uncle Bob gave me when he was home on leave, when she divorced my dad in '66. No clue who she gave them along with all my toys and bicycle to. I suspect my then future step brother, possibly in a (vain) attempt to get him to like her and accept his da was going to wed her soon.
I still have the eight fingers and two thumbs I was born with. I don't recall any serious cuts from my pocket knives, (I've probably gotten worse paper cuts than I have knife cuts.) nor do I have any scars on my hands or fingers from using a knife. Traditional slipjoint and friction folders are safe to use, so long as you isn't a moron and try to cut something with the blade spine or stab something other that a

hotdog


or Italian sausage.
I've never
needed one hand opening, not even when working on a ladder.