Re: Your favorite seinen (and why)
These descriptions are littered with mild spoilers.
Gantz- This was my first seinen manga, and it quickly got me acclaimated to the differences between seinen and shounen. The unexpected plot turns, interesting characters, stylish weapons, random cover girls, well-done fights (it really does feel like they're struggling just to stay alive, let alone become powerhouses like osaka), and well-rounded cast all had me hooked in less than two volumes.
Berserk- I don't know if I really need to even list this one, since it's pretty much a given. Amazingly epic artwork that I could lose myself in at times, characters that are so well fleshed out that I feel as if I know them, masterfully done battle scenes and a gripping plot all come together to make this the best manga I've ever read, and I struggle constantly to try to find another manga that can match up to it. The long waits between releases are a small price to pay when compared to being able to read such a masterpiece for free.
Shamo - Just recently read this one, and I haven't had a whole lot of time to digest it mentally. It starts off interestingly enough, with a normal character performing a random act of insanity, followed by that character's journey through a metaphorical hell. Fascinating as it was in the beginning, in the end I became a bit disenchanted with it as it branched out into other characters (randomly training the main char in the mountains to face a foe that he never really hits more than once? really?), but since it's not over yet I have high hopes. The fact that the main character seems to have recently forgotten a lot of what he's learned is confusing me a bit, but I assume it'll all become clear in time.
Vagabond - This one is a bit odd for me. I know I like it, I know I enjoyed reading it, and that it was a hell of a ride. The only thing I don't know is WHY I enjoyed this manga as much as I did. Similar to Shamo, when the perspective switched to a secondary character (deaf guy, not Musashi's friend), I quickly lost interest since I couldn't see the direct connection to the main story line. Recently it's picked back up for me, and I'm into it again, but if Musashi really is crippled-ish for life, I don't know how the author will keep me that way.
Battle Royale - I loved this manga on the whole, but I grew tired of the constant backstorying. Mitsu as a villain was a bit over the top for me, but I suppose that her backstory was acceptable in revealing her whole personality. Overall I really liked the main characters (and Mim, who was pretty badass) and the villains (sans Mitsu), as well as the action, but I quickly grew tired of the constant backstories. Essentially, this is the quintessential must-read survival manga, period.
Ichi the Killer - I wasn't expecting much from this one, but it surprised me. Interesting characters without being TOO repulsive was a big plus, even if the ending was a bit of a cliffhanger (honestly, I feel like I just didn't read a final chapter, even though I clearly did). Excellent action, innovative weapon's on our protagonist(?)'s part, and the pacing all made this manga well worth the read.
Elfen Lied - I didn't care for this one, although a lot of other people seem to really dig it. On the whole it seemed like it was just a bit too much like a Shoujo with some random dismembering, and the plot slowed to a crawl near the end.
Ubel Blatt - I recently gave this one a try, and after a rocky start (the prologue sounds like some sort of wannabe LotR knockoff) it really got me hooked. The depth of the main character is offset by his single-minded determination to exact his revenge, and I very much get where he's coming from (in the sense that I often ignore all the complicated factors of a situation and just focus on what I was after in the beginning), and the action scenes are above average. Not many people seem to like it, but odds are they're comparing it to the likes of Berserk, which really isn't fair for a manga that's less than fifty chapters along. Having said that, let me directly contradict it by saying that unlike Berserk, I don't think that this particular manga is worth the long intervals between releases.
This topic was a good read. I've picked out a few new titles that I'll definitely be giving a shot, thanks all for writing such detailed responses.