You don't want my whole list... I have some universals I play with for every farmer and some that I focus on with each individually.
The biggest QOL changes i consider essential:
Automatic Gates
NPC Map locations (sometimes for a bit of immersion I don't load this until I'm a few seasons in, or try not to look at it, as early on the farmer knows nobody...)
To Dew
Better ranching (Puts an empty heart above the animals you haven't petted yet, and flags the need to milk or shear as well. A lifesaver if there are a lot of animals. Or a lot of deep grass...)
Submerged Crab Pots (The plus side: crab pots with bait in are shown by a bobber. Crab pots with a catch are shown by a bobber that moves slightly differently. Only empty crab pots are visible. The down side: you don't know what's in the pot until you empty it. I liked that it wasn't just a "makes life easier" mod, but it looks a lot better at the Moonlight jellies to see a few bobbers and not a hundred crab pots...)
Realistic Seasonal Shop Inventory (Another one with deliberate pros and cons. Changes the items in the shops a bit, including upper limits in how many you can buy per day. Pierre has fewer seeds on a given day, but the selection changes daily. Gus serves more dishes with seasonal ingredients. Clint sells less raw ore but more (overpriced) bars he's already refined for you, and some (wildly overpriced) bombs. I have to admit, I tweaked the code in this a bit to suit my personal preferences past what the mod configuration does, so it feels odd to recommend, but it seems like the best shop change set that's 1.6 friendly.)
Visual and aesthetics stuff:
Diverse Stardew Valley (configurable changes to the characters, including race or cultural variety, disabilities, and a whole whack of seasonal outfits. Mostly visual but includes a bit of dialogue as well.)
Visible fish (shows which fish are found in a given area. Doesn't show them coming TO the line or anything, though)
Like a Duck to Water (causes ducks to swim more, especially right *after* being petted, when the farmer can see but isn't inconvenienced by it.)
Forest Junimos (there are junimos in cindersap and more in the secret woods. Like SH's Wild/domestic animals, pretty much just visuals to make the game more immersive.)
NPC related stuff:
Canon friendly Dialogue expansion (once you're bored with dialogue from the vanilla crew, this freshens it without including many lines that would grate against most folks' personal idea of the characters.)
The Ranch Expansion (builds on Marnie and Jas mainly... you'd think these are meh characters to highlight, but that's the point; this gives them attention they need. OTOH, it's mean about Lewis.)
Jorts and Jean (They're cats. They talk. It's hilarious, and the Stardew revisioning of the real world "Jorts margarine incident" still makes me laugh... And yet, they have at least two cutscenes which are tearjerkers. Plus they agitate for a union at Jojamart! Better jobs for Shane and Sam!)
I've tried a lot of different new NPC mods and other vanilla dialogue or event expansions, though; it's probably my favourite area. But I do them a few at a time, not all of them for all farmers.
Of the town-sized ones I've tried, East Scarp is closer and better integrated with the vanilla game than the others, giving you more reasons to go there and more distinctive characters. (But I haven't done SV Expanded or Ridgeside Village or Sunberry. Yet.)
Similarly, if I expand on other stuff, I do different crops/animals/fish/gems/visual tweaks for each farmer rather than piling on a million changes all together.
And yes, this IS the short list.
