Fuuun Ishin Dai☆Shougun

Similarities: Both have the same mecha, harem and ecchi genre. Both have the same guy character who is a delinquent. Dissimilarities: One the main guy in one anime is still a virgin, while the main guy from another anime is..................I don't know, maybe he has gotten laid. The main girl character in one anime has to serve as the guy's play thing......to increase his "Hi ERO" powers, while in the other anime the girl co pilot serves as the guy's.............I guess we'll find out. The antagonist in one anime where.....let's just say on the horny side, while the antagonist from the other anime where basically on heat.  

+ Making by same studio + Alot action + Fanservice everywhere (you can skip if you want) + Harem element + Kazuya-Satellizer & Kiriko-Keiichirou IMO is similar, both protecting is each other when in dangerous just like lover but not actually lover. Also they must dealing with some intruder in their realtionship (Linchen Rana & Chiharu) 

+ Story taken place in japan 17-18 century + Fanservice everywhere (you can skip if you want) + Alot action scene + The main character is faced with a conspiracy plan 

The Main characters in both series must give up something in order to keep their powers. Both taking place in an historical setting. Dai Shogun takes place in Edo Japan during the Shogunate era. While Maria takes place in an Medieval setting 

Mecha, Action and Ecchi in both. Both males are capable fighters in their own right and likeable without many shounen cliches. Both males have a female watching over them stopping them from getting into any potential dangers and mischief. More similarities to come as the show progresses. If you like one I do believe you will like the other 

They are both mecha anime that took place in ancient history. The protagonists in both anime believe they are the greatest men in the world.