 If you liked
Sirius
|
 ...then you might like
Kaizoku Oujo
|
Both are original anime series with similar themes.
In both series there's a worldwide hunt for something which will change the world. There's a distinct sense of some greater goal which will be discovered by the travelling ensemble cast by the end of the series.
While there are differences in the overall content of each anime, their similarities lie in their themes so if you enjoyed that part I recommend watching the other.