Tenchi Muyou! GXP

The main characters of both series are very similar, except for the invincible bad luck of Yamada "Lorelei" Seina. Besides that, these two causes a lot of trouble which make you laugh at each episode! For the fans of harem-style that like sci-fi, you must try Dual! too! Romance, comedy and amazing mecha battles awaits you! And if you watched Dual! and are looking for a reason to watch Tenchi Muyo GXP, maybe you can spot an old mecha-friend in the last episodes of this series... 

The main characters in GXP and Captain Tylor have simple dumb luck which allows them to survive dangerous situation without skill.(In GXP Siena has bad luck, yet in the end he survives.) Both of the anime involve space battles and have harems. One contrast between the characters is Captain Tylor has a happy-go-lucky personality while Seina(GXP) is a worrywart.  

+Also story plot of Tenchi +Also Ecchi, Comedy , harem +Also about a boy with a Women all around him +Also about space, mecha, spaceships All along anime is very similar , more or less have same Ecchi humor, same girls that are in love with he boy.  

The main male character has nothing but bad luck. The upside is he is surounded by beautiful girls. Hey who doesn't like some unwanted distruction in there lives 

These are two animes that in my opinion have a very similar humor to them. It's one boy living with a lot of hott girls and things have some.... sexual tension. It's perverted, but in a funny way. If you like one odds are you will like the other although I prefer Tenchi. 

If you like the idea of being one man with countless beautiful woman fighting over you, then you will enjoy these series. If it intrigues you even more to have to fight a war in outer space while fighting off advances from the girls, you'll love these series. 

Same feeling and the stories are quite similar.  

It gives of the same feeling. Normal kid gets into a world of space battles and attains powers and position that he thought where impossible for him. 

Both are harem shows that try to run something like a plot as well, as the usual fanservice