Tenkuu no Escaflowne, Koukyoushihen Eureka Seven Recommendations
This anime is similiar to Eureka Seven in the fact that there is main mecha (like Nirvash) that is awakened by means of both main characters, Van Fanel and Hitomi Kanzaki. Both anime have a mythological genre as well, and both rely heavily on romance as well as a unique plot line that is unclear at the start, but reveals itself as the anime continues.
This isn't on here yet!! Both use the huge human-form machines to battle and fly in, Eureka Seven "surfs" or "refs". Both have a wonderful coming of age story with a sweet love story (Escaflowne leans a bit more on the love story).