You probably have heard of it! "Ten-seventy" is the 1991 big black box (New Easy-to-Master D&D Game). "Eleven-six" is its smaller repackaging (Classic D&D Game, the 1994 tan box / 1996 small black box).
I voted BECMI, but if we're going to treat Moldvay/Cook and Mentzer as separate editions, I'm not actually running either one. I run 1070/RC/WotI. The 1992 and 1986 Immortals rules are more different from each other than the 1982, 1983, and 1984 Expert Sets are.
Beyond the Wall / Through Sunken Lands. Most would point to the playbooks or the "build the village" mechanic as the selling point, but for me, it's the magic system.
BtW/TSL is like a B/X clone that caps at 10th level, with three core classes (fighter, rogue, and mage, where the mage also...
Advanced Labyrinth Lord / Advanced Edition Companion is the same. Outright says that you can have an elf and an elf fighter/magic-user adventuring next to each other and it'll work out just fine. And it does.
I like to conceptualize cure light wounds as curing wounds to both body and soul. The spell both heals bruises with divine magic and lifts weary spirits like a kind word or a bit of sage counsel. Makes it feel like something Gandalf might do to subtly pluck up the mood of a homesick hobbit.
I remember these clones from back when. And the drama.
But it's understandable to me that a Holmes clone won't usually get a lot of attention. The Holmes rules are a subset of the LBB + Greyhawk rules plus a handful of idiosyncrasies. You can make a Holmes clone for the sake of preservation or...