It’s a tough question.. there’s several genres that I like which are kinda dissimilar or otherwise incompatible with each other. For instance, I really liked Fullmetal Alchemist, FLCL, Trigun, Rahxephon, and Hellsing.. but none of those are cute like Minami-Ke, Haruhi, GochiUsa, Hataraku Saibou, Blend S or New Game!.
To make a top-5 of anime of all genres is kinda silly.. but I can still try i guess.
It’s difficult.. If someone were to ask me again next week, the list might actually be different. But the thing is that I’ve watched hundreds of series and again they serve different goals. Slice of life shows are for relaxation, while some others were watched due to the awesome BGM, and others were watched for the feelings they conveyed. “anime” is not a genre of TV series; they are TV series per se and have many sub categories of their own. In that respect, Non non Biyori is the only one on my list that is a relaxation show.. the others are all very heavy story-driven or emotional.