>>1473051Twelve Kingdoms and Rayearth suck. That said:
The Aquarion trilogy, the original Zoids, Big O, Dai-Guard, Neo Ranga, Big O, Blood Plus, Redline, Canaan, Gosick, Godannar, Gravion, Gun X Sword, New Getter Robo, Shin Mazinger, Steel God Jeed, Gaiking: Legend of Daiku Maryu, Betterman, Cyborg 009 vsm Devilman, Mazinkaiser SKL, Escaflowne, Gundam Seed and Destiny, Gundam 00, Gundam Build Divers, Yamato 2199, Haibane Renmei, Steamboy, Your Name, Weathering With You, Samurai Flamenco, Nobunaga The Fool, Aldnoah Zero, Captain Harlock 2013, Akudana Drive, Babylon, Star Driver, Flip Flappers, Fafner in The Azure (mainly the sequels but the first is mandatory), Freezing, Beast Tamer, Re:Monster, Chaika, Maria The Virgin Witch, Mysterious Archive of Dantalion, and Metallic Rouge.
If you're ever in the mood for something more vintage try out Ryu Knight, Granzort, Braiger, Goshogun, Groizer X, Steel Jeeg, the original Casshern, Orguss, Acrobunch, Dorvack, Fighbird (it's where the Is This A Pigeon? meme is from), Da-Garn, Raijin-Oh, Ideon, Xabungle, Dunbine, and God Mars. On top of all these Grendizer U is about to air this Saturday and might be the final TV series with manga legend Go Nagai involved and since it's a remake no you don't need to see anything else.