Most of my farmers are just loose projections of me, but some do develop and evolve into their own sort of character.
My original farmer is Salty of the Funny Farm, which started out innocently enough as your standard novice farm, grew into a general little-of-everything farm, and has ultimately turned into a massive slime ranch with multiple hutches and a single dinosaur coop, garish decorations all over, and trophy giant pumpkins. Salty originally crushed on Caroline, then pretty much immediately pivoted to courting Abigail in some warped sense of revenge - which ultimately turned out pretty well for him (the giant pumpkins are only there for Abby, that's how dedicated he is!). He also befriended the Wizard very early on and learning more about the potential relationships between all these characters put him in a bit of an awkward spot, but one he's not interested in changing or worming his way out of now. It's all weirdness down at the Funny Farm, and I feel like that's only fitting.
My favourite farmer might be Sab, though. I wanted to make an orchard farm on the forest map, and set myself with the restriction of not being able to buy any seeds - the only thing I could buy from Pierre is fruit tree saplings, since there's no real way to get them for my orchard otherwise and she otherwise thumped her nose at all merchants otherwise and only drops product in the shipping bin. She was originally intended to romance Elliott in my head, but the course of play changed my perspective for a few reasons. First, since I couldn't buy seeds I found myself going for the mixed seeds by hitting as many weeds as possible in the mines. As a consequence, this was the first farmer where I got really good at combat with. She left all my previous farmers in the dust, and combat was her first level 10 skill (something which has yet to recur with any of my other farmers). She's also the only farmer I really enjoy using hammers with. As a result, my mental image of her went from being a gangly fruit loving gal to a beastly queen that most would suspect to be on steroids. Now, at the same time as this, Elliott was never around when I was out looking for him, but Alex would be around and get chats along the way. Eventually, Alex supersedes Elliott in hearts even without as much gifting, then Alex's eight-heart event comes around and I go "eh, why not?" Now, they are the most muscular couple in the valley and Alex pipedreams of a day when he can watch his daughter (that's right, not his son!) be a gridball champ. Excellent plot twist.
Calanthe runs a fish pond arrangement on a riverside farm, and all other available spaces are dedicated to producing tea and honey. My head canon is that her grandma was a mermaid and part of her calling to the valley was to get closer to the sea again. Always wears beach clothes and I like to imagine she sings for all her fish (which makes rainy days great, since I can imagine they are singing back). Part of me would like to redo this farm over again on the beach farm map, but riverside still has a certain charm to it (and I ended up making my beach farm a duck farm, which I haven't done yet, so that's been a nice compromise).