I don't think there's one anime I hold in the highest regard, there are multiple favourites for a bunch of different reasons. If I had to speak objectively, I guess Steins;Gate and Hunter x Hunter, as both actually improved the source material for the most part and have a great story and characters overall. FMA:B was great too, though it did profit from very strong source material already. If we're talking about romancy stuff, that would be Yahari Season 2 and Toradora, Kokoro Connect was very interesting too. The Fate franchise is my biased favourite, though only the new anime and Fate Zero count, bc the original anime by DEEN is shit and does not exist~
If we're talking about life lessons and a strong philosophic approach then nothing beats Mushishi.
AnoHana is actually the anime that made me cry the most, though it's a hit or miss for most people I feel.
Nothing does comedy quite as well as the Gintama franchise, and it's supported by strong drama arcs.
The Monogatari franchise is very unique and just has something for everyone.
Hellsing Ultimate and Kill La Kill are great action flicks with a lot of insanity or just being nicely over the top/ridiculous.
Paprika and Okami Kodomo probably are my favourite anime movies.
That's what I can think of from the bottom of my head
