I was thinking of how I found some of the ones I've really enjoyed recently. Mangadex has a decent filter system that can have inclusion and exclusion criteria, like must have ninjas but can't have lolis. And the most important criteria of all: only showing ones that are completed. Some of us aren't made to read things as they trickle out only to have them suddenly cancelled (looking at you, Dress up Darling).
I just use it to describe what I'm looking for and then sort the results by rating. That's how I came across Alice-san Chi no Iroribata (others have mentioned it) and Ao no hana.
For ones not mentioned elsewhere:
Sono Koi wa Ichigo no Youni - Strawberries and farming and romance.
Insomniacs after school - I usually can't stand a school setting, but really enjoyed this. Astronomy themed.