If you liked the Interstella 5555 - The 5tory of the 5ecret 5tar 5ystem anime, the Anime-Planet community thinks you'd like:
Several months after battling with Kamjin, Lynn Minmay puts on one last show in Macross City, reminiscing about all of the past events that she and the rest of the gang have gone through together. Meanwhile, the Megaroad-01, a colony vessel commanded by Misa Hayase, prepares to launch into space on a new goal: to spread humanity across the stars and further explore the vast universe.
Both anime take on telling a story through songs. While the songs are completely different genres they both share a sci-fi theme. I wouldn't suggest watching Flash Back 2012 before watching the macross series but if you liked it you should enjoy Interstella 5555.
No longer held back within the confines of Earth, space exploration is now commonplace throughout the universe. These new colonies, which make up the "New Frontier", are now home to the masses, but the evil mastermind Nemesis and his Outriders spread destruction throughout these worlds. In order to protect the citizens, an organization called Calvary Command was created to bring justice to these outlaws. Saber Rider and the elite agents known as Star Sheriffs now stand between the renegades of the universe and total chaos. Power Stride... AND READY TO RIDE!
These two anime have a really matching animation style, and if you look deep enough at the plot, you might find similarities. They take place a bit in space, in other universes, and in Earth; both parties are threatened by an unknown evil and are made up of three boys (who are smart, silly and beautiful) and a girl; and both girls have a secret fan, who tries to win her heart and save her at all costs. Look closely and I think you'll understand why they're so similar. I think you'll enjoy both of them if you don't hate mecha anime, as "Saber Rider" has some of that in it.