Chobits. It's adorable, funny and has such a sweet message about true love. While it plays on sexual notes ultimately it shows that love isn't about sex and can be achieved and maintained without it. I'm not saying people should be in sexless relationships, I do believe it should be an addition to a good solid relationship.
Second favorite would be Full Metal Panic. It has the perfect combination of action and comedy. The characters are very loveable and several parts had me laughing for five minutes strait ^_^ It always has me hooked for the next episode.