Str for fighters! Also roll d100 if you are lucky enough to have an 18, because sometimes it's a shitty 18 and sometimes you are an unstoppable engine of destruction! Only if you're a fighter, though. Only fighters can be that strong. Don't be ridiculous.
Dex for everyone! It's just free AC, which you absolutely need as much as possible because every time you get hit it's the end of the damn world!
Con for everyone! Only to 16 for non-fighters, though, because it just wouldn't be fair for a Con higher than that to apply to anyone else.
Int for...Wizards! Doesn't mean shit to anyone else until they're getting their brains sucked out by Mind Flayers (though if you're fighting illithids it mostly means your DM hates you so you're screwed anyway). But you better have an Int of 17+ if you want to not suck at wizarding.
Wis for...Clerics! God hates everyone with a wisdom under 17. You could argue that it's also for Paladins and Rangers because they get "spells," but only if you hate your paladin and ranger friends and want them to waste their turns casting shitty spells instead of doing anything at all that they're any damn good at.
Cha for...christ, you're not playing with a Bard, are you?