In my “ideal’ Dungeons & Dragons house rules, there are four ability scores. The value of each is generated randomly by rolling 3d6 (in order), and the player is given the option of “swapping” one score with another, once. If the average of the scores is 9 or less, the player can generate another list from scratch. The ability scores are:
When converting from the standard D&D six ability scores/attributes, I take the highest of Strength or Constitution and the highest of Intelligence or Wisdom. I suppose you could take the average instead.
This has come about by influence of Into the Odd, which reduces the number to three — Strength, Dexterity, and Willpower. ItO’s minimalistic approach very much appeals to me, though I do cause to split that last entry — I believe in the newer version of the rules being playtested it’s changed to Charisma, and I don’t know that either Willpower or Charisma on its own is sufficient. It’s also influenced by a game of Crypts & Things that I ran a while back, and gauging new players’ confusion about the standard six attributes. Throughout the game, we kept adjusting the character sheet. We changed the names of some of the stats to make it easier for people to read and understand at a glance — Armor Class quickly became Defense, for example — and outright ditched some of the other bits (C&T’s sanity stat, for example, just didn’t fit the game we were playing and wasn’t being used). New players were often confused by the difference between Intelligence and Wisdom, and although I originally gave them the old “tomato” line about it, eventually I just quietly folded the two stats together into Mind. This made even more sense considering that Clerics are not a core player-character class in the C&T rules. Thus emboldened, putting Constitution and Strength together was an easy next choice, since Constitution is famously used for Hit Points and not much else. The term of the remaining stat itself — Strength — I’m not as certain about. “Body” would seem to overlap with Dexterity, which I want to keep distinct, and while “Brawn” would perhaps be more to the point it isn’t as catchy for me. So, Strength it has remained for the time being.
I think that having the four ability scores makes sense because it retains the Mind/Body symmetry one sees in the original game, while simplifying things that could be potentially confusing or needlessly complex.
This isn’t exactly a revolutionary change, of course: it’s just what makes the most sense to me for my game.
(I should also note that I have not used this as a house rule for 5e, which I have not been able to run or play yet. The above is what I’ve done for more generic “D&D” games and OSR games. I’ll probably be playing some 5e after my current run of The One Ring, and will start out playing rules as written.)