Okay, I must admit that the title is abit clickbaity. I do not dislike the classic six D&D stats. They are only tools. And - in my opinion - some of them may be replaced and others repurposed to make (my) games more interesting and make all their mechanical aspects easier to resolve.
Constitution (CON) - this stat devours and incorporates the Strength and becomes the general description of one's physical strength and toughness.
Dexterity (DEX) - nothing to see here, move along. Or rather, in some games, DEX was used to determine the ranged attacks, while STR was used to hit an opponent in melee. I find it, well, stupid. So, in my games (non-OSR games, as within the Old School I always stuck to 0e) DEX always was used for melee (and dodge, and of course som other non-combat actions). This brings us to the next stat.
Perception (PER) - I always thought that lack of ability that clearly described one's senses was the biggest flaw of D&D (and WFRP as well, but that's another story). Thus, behold the Perception! Easy to use in ranged combat, easy to use for well, spotting things, hearing things and, uhh, tasting things? Okay, that may be a little too far.
Willpower (WLP) - you may view the Willpower just as the classical Wisdom. I just changed the name to make it more fitting its purpose.
And... that's all! Or maybe not, as I like stats. And I like stat-based games and resolution systems. That's why the second edition of Terminal Space will be based on Knave. To make it even faster and easier to use. So, here are some additional ideas for the statistics:
Tech Level - I used it in both Terminal Space and Bandits and Battlecruisers. Randomly determining one's technological prowess always led to some hilarious results. Also, it fitted the genre really well.
Charisma - extremely useful in most games and/or settings. So, you may ask, why I omitted it? Because in some settings. worlds and circumstances, it becomes quite obsolete. For example, robots aren't very sociable, so in settings devoid of humans (and elves, dwarves and so on) CHA isn't very helpful. That's why I got rid of it in Pain.
Faith - can be used to describe the character's closeness to a god (or gods). Perilous Ages had some other minor mechanical benefits relatable to Faith's level but in more magical settings I would use it to affect one's ability to cast clerical spells.
Sync - very open idea, created for use in Pain to outline one's attunement to the mystical powers of the City. Here (page 3) I've added some additional ideas how to use this stat in your games. Fueled by Pain is percentile ruleset but hey, it doesn't really matter in the matter of the character abilities.
Oh, and the last thing - you may ask - WHERE THE FUCK IS INTELLIGENCE? Well, nowhere. I dumped it. INT is absolutely and utterly pointless, maybe except the situations when you roll it really low, which forces you to roleplay an idiot. But aside of that, it doesn't have many good uses (at least in my opinion). Extracting some information from the GM isn't one of them. If you're stupid and your character isn't, it won't end up well. And I ran games for some, let's say, not very bright individuals (and - to be perfectly honest with you - I like both them and the memories of our games) so it's way easier to remove the PCs intelligence score, thus balancing it with the one of the player.
Sheesh, I think this post is quite gibberish. I sat down and wrote it on the fly, without any previous notes and similar stuff. So, if something is totally unreadable or unclear - let me know!
