Good completed scifi/fantasy anime?

Quite a list. Two I would highly recommend would be Steins;Gate and Erased. Both deal with time travel and are both really touching, especially Erased. Steins;Gate is pretty complicated and has a beautiful ending and a good amount of intense moments. Erased is one of my favorites ever, even though it just ended 2 weeks ago, great plot, great art, great soundtrack, and just really sad, thrilling, and touching.

Owari no seraph- The story follows the story of a 12 year old boy named Yuichiroa. He lives in a world were a virus has spread and killed everyone except children 13 and under. Then vampire swarm the earth and claim it. Then they take the children underground to protect them from the virus. In exchange they must donate their blood. If they refuse or defy the vampires they will be killed.

Fullmetal alchemist Brotherhood -This is about two brothers Edward and Alphonse who lived with their mom and dad. One day their dad leaves for some unknown reason. Soon after their mom falls ill and dies. In an effort to try and bring her back they learn alchemy and try to perform a forbidden alchemic technique called human transmutation. This back fires on them. Due to the law of alchemy which is equivalent exchange (In order to get something, something of equal value must me lost) Alphonse lost his body and Edward lost his left leg. Edward also scarifies his right arm to rescue Alphonse's soul and seals it in a suit of armor.

Inuyasha- Its about a girl in high school that finds a well that takes her back in time. She meets a half demon named inuyasha. She learns that he was sealed to the tree for 50 years until she came and broke it. They travel together trying to search for shards of a jewel that is said to grant any wish you want. It was proven that anyone who comes in contact with the jewel will suffer a great deal of pain (a curse) The jewel waits for the one person who will make that one wish that will break the curse . 

Future Diary- This is about a boy named Yukiteru who is a loner and spend all his time writing a Diary on his phone. He also spends a lot of time talking to his imaginary friends Deus who is the god of space and time and his assistant Murmur. It turns out that these two were actually real. Deus gives Yukiteru a phone that tells him the future within a 90 day span. Deus also forces him to compete in a battle royal with 11 other people to decide who will become the new god of space and time. Each of the other contestants also have a diary that tells the future in a unique way. To win the completion you have to kill the other players and be the last one standing. If the winner is not determined within 90 days deus will die and the world will end.

Gokukoku no Brynhildr?