Kidou Shinseiki Gundam X

Both anime are about boy skilled in mecha operating/maintanence joining a "pirate" ship, whose purpose is deeper than it originally seems. They also have rather similar romance subplot. 

Both Start with a organization sought by the government (Gekkostate in Eureka Seven, Vultures in Gundam X) who try protect some special person/species (Coralians in Eureka Sevan, Newtypes in Gundam X). Progatonist, some secundary characters (renton = garrod, eureka = tiffa, talho = Toniya and Mischa = Techs) and your relationship are similar (GarrodxTiffa and RentonxEureka). 

Gundam X can almost be considered as the anime that influenced several plot aspects of Eureka 7. Garrod and Renton are very similar in the fact that they both join up with a group of individuals on a ship in order to protect a mysterious girl they immediately fall for (ie Eureka and Tiffa). 

Both feature stories where a teenage boy is swept up into joining a rogue group, piloting an exceptionally powerful mecha, struggling with finding his place in his new home, and falling in love with an emotionally distant girl along the way. The characters Jamil and Holland are very similar, both in their positions in the group, and relationships with and attitudes towards Tiffa and Eureka respectively. 

Both titles are similar in several aspects such as mobile suits, theme, and overall cast. I personally liked After War Gundam X and I very much feel it is the most underrated in the entire Gundam franchise with Iron-Blooded Orphans being my one favorite shows in Anime. The use of groups such as Teiwaz and Gjallarhorn in Iron-Blooded Orphans can be compared to as the Vultures and Earth group in Gundam X. While the MC in both series are differentiated as Mikazuki is somewhat more of the stoic and battle-driven as compared to the more expressive and rash Garrod. They both also have what you would call a waifu whom both MC need to protect and reach her destination that is integral to their overall goal. Although IBO plays a darker theme with its use of child guerillas and sense of family as compared the more light-hearted Gundam X that is more focused on the concept of Newtypes and Stopping an inevitable war between the Earth Group and Spacenoids. Ultimately, if you somewhat enjoyed the first season of IBO, then strongly recommend that you give Gundam X a watch.  read more