Have not seen Linebarrels of Iron, but Have Basilisk and Casshern Sins. I will say that Casshern Sins is way better than Basilisk and Linebarrels of Iron though - Casshern Sins is an emotional, character building show that is trying to answer what it really means to be alive and mortal rather than a 'dead immortal' being. It feels most akin to Ergo Proxy - having as a slower paced, dark atmosphere but with a lot of heart and soul searching. It's not as complex as Ergo Proxy, but is a much more emotional and sad series - especially towards the end.
It's a pretty sad series that you would want to follow immediately with a comedy or fun adventure series. The first time I tried watching Casshern Sins the first episode was where I stopped. Just couldn't get into it - it's a series that you have to be ready to see, not one that can just be watched at the spur of a moment. The second viewing was when I was prepared for a darker, sad, and thoughtful series to watch and it has become one of my favorites.
Highly recommend Casshern Sins if you are in the mood for an emotional ride and some thoughtfulness in a series and don't mind the ever present semi/graphic violence and a some sexual content (nothing shown) along the way. It's better than Ergo Proxy for emotional content, but Ergo Proxy is the more polished and complete series with much more complexity of the characters shown.
There's a section of the show told in a song a little before halfway through the series that is a perfect expression about what Casshern Sins is about, through both the songs lyrics and the visuals.
No major spoilers either:
http://www.youtube.com/watch?v=DX6r7YXWLic&hd=1