Some warm and enjoyable anime, mostly slow-paced. Some of them have meaningful (albeit simple) themes, some don't, but they're all just so nice!
I've ordered these somewhat, although it's difficult to do so. At the least, I'd probably say Aria-Kokoro > Usagi-Manabi > K-on-Minami-ke.
Of course, I only included first season of any multi-season anime. The Aria series just keeps getting better imo.