Slice of life for me is about characters doing mostly relaxing and sometimes funny things - some funnier than others. Warm fuzzy feelings probably next.

Non-Non Biyori would have to be my favourite slice of life.
Natsume's Book of Friends was good too, if you can call it that.
Minami-Ke was good on/off.

^ That's talking about longer running series, short series I tend to forget but can also be good for their run.

Kobayashi is up in the high ranks too for me.