I'd have to say no series is like Elfen Lied. Speed Grapher is pretty gruesome but the theme is very different. KGNE is fairly close in some ways, but it's also very life-like. Saikano has a happy ending imo, while Elfen Lied has a very sad and sympathetic ending.Originally posted by: Ryllharu
Too be honest, there really isn't anything that similar to Elfen Lied. It's about as far from any series done before it due to the amount of violence with the romance that's piled into it as well.
The closest analog I can think of would be Speed Grapher. That has the same sort of groteque violence and disturbed individuals that Elfen Lied had. Berserk would also be another series with that same vein of violence and disturbing relationships involved. Mai Hime toward the end had some similar elements, but no where near the scale that these two did.
If you're implying in any way that people who'd like Ai Baby would like Elfen Lied necessary, as you stated the inverse, there's no way. On your same lines of thought, a more mature series like Kimi Ga Nozomu Eien or Saikano would be more appropriate.
Elfen Lied is truly unique in terms of what it brings as a whole package. Its individual aspects have many flaws, but the way everything is presented is what makes it amazing.