Recommendations by Nomori

Expansions and NPCs

Stardew Valley Expanded - One of the biggest expansions which seamlessly blends into the vanilla game, adds new questlines and interesting characters
East Scarp - adds a neighboring town with it's own NPC, also works as a basis for many standalone NPC mods, most notable of which are Always Raining in the Valley and Lavril
Adventurer's Guild Expanded - expansion for the Adventurer's Guild, new questline involving studying monsters along Marlon's nephew and niece
Romanceable Rasmodius SVE - more content for the Wizard is always welcome, especially if you turn him into an amazing Witch Rasmodia
Lannah - Female Lance from SVE - want more witches? Here ya go
Mister Ginger and Tristan - just a cute cat and an old man, yep, definitely just that
Lunna - just a cute.. okay I'll stop

Lookup Anything - tired of searching the wiki for gift tastes? Put the wiki in your game and automatically search everything by clicking a button
Event Lookup - same as above but for event, I also recommend Event Lookup Locations to fix some of the weird map names
Chests Anywhere - stop running between the town and farm to get that single gift, with this you can access you chests from anywhere in the world
NPC Map Locations - shows NPC's on the Map, make sure to also get Custom NPC Map Locations for those added NPC's
Friends Forever - everyone needs their alone time, right? That doesn't mean you're growing apart
Auto Animal Doors and Automatic Gates - why would you need to bother with opening doors, get those truffles quicker
Bigger Backpack - Pierre forgot to put on display his best backpack, let's remind him
Better Chests or Convenient Chests - take care of yourself, stop jumping between you wooden boxes and just use auto sort into chests
Generic Mod Config Menu - I'm sure you love digging through your mod folder to find that one config. No? Here ya go then

Walk of Life - ever wanted to become a god in a fairly balanced way? Now you can, basically a more interesting skill tree with the possibility of stacking bonuses
Automate - make the most out your limited space and forget about filling those hundreds of kegs by hand, industrial revolution in the valley the mod
Tractor Mod - if automate doesn't satisfy your need for technology get yourself a farmer's best friend
Free Love - all hail polygamy! Just in games... don't sue me
Mail Services Mod - remember Junimos? They fit perfectly into that little mailbox of yours and do wonders with gifts
Robin Work Hours - Robin... for Yoba's sake... stop banging that hammer when I sleep!

Vanilla Tweaks - those strawberries never looked better... oh yeah, and like 90% of other items too
Aesthetic Garbage - need I say anything with this name? You need garbage in your life
Seasonal Japanese Buildings - for your perfect anime fantasy, or you know... just a damn good looking buildings
Seasonal Outfits and it's addon for SVE - change those clothes people!
Simple Foliage - what those vanilla trees looked like again?
Domestic and Wild Animals - after installing this you won't know how to live without cute otters swimming around while you're fishing
Unique Children - whose that kid?! He looks so generic! Oh wait... not anymore
Visible Fish - ever wondered how deep is that river cause you can't see a single fish? Well, now you can
Interior Mods I always use:

Sprite Master - cut your loading time by 1/3, side effect is the game looks like it's been scrubbed clean of any pixel, but if it's not to your taste go ahead and disable filtering in the config, you'll keep the optimization part