I forgot to mention this earlier, but another steel at the top of my list is DIN 1.4110, the steel that Victorinox has used for decades to make their Swiss Army Knives, for all of the same reasons why I love 420HC.
In fact, it's highly likely that DIN 1.4110 has cut more things in my life than any other single steel, because the knives I reach for first for the vast majority of tasks outside my kitchen are Victorinox Swiss Army Knives. It's highly stainless, extremely tough, easy to sharpen, inexpensive, widely available, and polishes to a mirror smooth finish that is very attractive for an EDC.
This year, I made the decision to change out (as soon as budget priorities allow) the vintage Gerber Harsey AirFrame I've been carrying as my "big EDC" knife for over 20 years, and replace it with a Victorinox 93 mm Alox model, likely the new(ish) Companion Slim Alox. Why? Because I pretty much never use the AirFrame, since 99% of what I need a knife for in my daily life is covered by my Victorinox Rambler, which is my primary EDC knife, and for anything I might need a larger knife to do, I've been carrying my vintage Benchmade 100RR River & Rescue fixed blade knife. The Companion Slim Alox is much lighter and smaller than the AirFrame, and really, in civilization, the scissors, bottle opener/flathead, and package opener/Phillips are all I need from a pocket knife. Between the Rambler and the Companion Slim Alox, I've got redundancy and two different sizes for different sized tasks. Too bad they still don't make a Rambler Alox or a Cadet X Alox, because a Cadet X would be just the ticker.
And as Felix Immler and Roman Kase have shown, DIN 1.4110 is a very high performance steel.
Don't get me wrong, there's a MagnaCut knife on my wishlist, specifically the MKM Pocket Tango 3, to replace the old Benchmade, but that's purely because I like that knife design for an in-town EDC fixed blade, and I'd happily buy a cheaper steel version of it, if DCA and MKM would ever deign to offer one. I'm sure MagnaCut is a great steel, and it seems to be living up to the hype, but its performance doesn't really justify the price it costs. In-town EDC carry is the one purpose for which I think a super-steel is justifiable (for me).