I think having different subtypes of each personality is definitely the way to go. That way - not every villager's dialogue of the same personality type is the EXACT same. It would be nice to have diversity within personality types, so in cases when you have multiple villagers of the same personality type in your town, they wouldn't be exact carbon copies of one another. (which kinda ruins my immersion tbh) And another positive thing about it is that you wouldn't be able to have every subtype of every personality type in your town - due to the 10 villager limit. Which would in turn make visiting other people's towns more interesting so you can see and experience the other personality subtypes and dialogue.
Some ideas of subtypes... One half naming what I've kinda observed already being in the game, and a possible alternative subtype to that. It would be nice to have ATLEAST 2 subtypes of each personality type, but 3 or more subtypes would really diversify villagers and dialogue an exponential amount.
Peppy - popstar/idol
Peppy - manic pixie dream girl archetype (kinda crazy?), maybe impulsive?
Normal - smart/bookworm
Normal - Shy/sweet/maybe unsure of themselves/needing encouragement
Snooty - Regal/sophisticated/stuck up, acts like they're above you, bit prissy and scared of bugs and dislikes nature, can't stand gross/dirty things, is dramatic and thinks everyone adores them. when you get closer they try to be nice to you but just genuinely suck at being nice. tries to help you out/but accidentally comes off as insulting when doing so, but generally has good intentions behind everything they do once friends. (think maybe effie from hunger games?)
Snooty - fashionista, makeup/clothes orientated, dreams to be a fashion designer or model, a creative, bit nerdy about fashion, eccentric, and a go-getter (think labelle/label)
Uchi - Total tomboy/likes to rough house/bit of a prankster/jokester/messes around with you a bit, but in a friendly way
Uchi - Complete big sister vibes/ wants to protect you/sees you as family/pretty much looks out for everyone especially the shy normals and lazies/stands up for others, and calls out crankys/snooties types if they're being too harsh
Cranky - old man/ out of touch, cranky but sweet. dad/grandpa vibes
Cranky - Aloof, tsundere, maybe a bit of a mysterious bad boy?/ kinda shuts people out, takes awhile to get them to trust you and open up and finally reach their sweet side, appreciates your friendship so much once achieved, and maybe apologizes a lot for their past behavior? or just really appreciates that you put up with them being a jerk for so long
Lazy - Bugs/weird/semi gross
Lazy - Food/Sleepy/Cute
Jock - Super into being buff and swole, pretty much a gym bro, a little too into himself and his appearance, overly confident - but tbh doesn't live up to it lol
Jock - Promotes healthy active lifestyle, maybe slightly less obnoxiously, more into healthy food and nutrition side of things, wants to encourage you, big motivational speaker but in a good way, reliable, but still a bit of a bro
Smug - hipster/ appearances/wants to be cool and suave, massive flirt
Smug - kinda nerdy and pretentious - but mostly nerdy, gets a little too into their hobbies but in an endearing way/likes having intelligent conversations with you, and appreciates you for letting them to indulge in their nerdy side