It's interesting to get other people's perspective on what defines Guts. Personally, I think that image is a little loaded to work as a portrait though—the beads of sweat, and the look in his eyes has a contextual meaning that's specific to that one scene, and not to his character as a whole.
Really, there are so many colored images of Guts that it's more likely that I'll choose one of those over anything just black and white.
Instead of getting hung up on him though, what about all the other characters?
I like the ones people have posted so far!
I'll contribute with some other ones I think are good too:
Thanks! You just did a lot of the work for me. Most of these I'd also chosen, or at least set aside in a special folder for consideration. I'll give a per character breakdown on my thoughts:
Casca1: This is also the color one that I like, and will likely choose.
Casca2: Could also work, though I gravitate to her Falcons persona more right now, since her current look and persona is a little transient
Charlotte: Doesn't resemble her enough, even though this came from Miura's own hand
Carcus: I don't think a smiling picture of Carcus is definitive for him. A scowl maybe. There is another color illustration by Miura that works a little better I think.
Farnese: I actually prefer the one in the inside corner of Volume 24:
http://www.skullknight.net/encyclopedia/world/characters/farnese_small.jpg Mostly because it's not as contextual as the one of her next to a fire
Godot: I like it, I only wish it were higher quality and less grainy... Miura needs to release another artbook...
Griffith: I prefer the one I chose earlier. Similar to what a member said of Guts earlier, I think the one you've chosen looks a little too altruistic. The look on his face doesn't convey all that it could about Griffith's character.
Irvine: Yep.
Isidro: This might be the best choice. What do you think of this though?
http://www.skullknight.net/encyclopedia/world/characters/isidro_small.jpgJill: I wonder if a black and white illustration would be best. This one hardly resembles the Jill I know.
Judo: Yep.
Locus:Yep.
Luca: Maybe. Though in color, I don't think it captures her well.
Nina: Same as above.
Pippin: It's a toss up between this and
http://www.skullknight.net/encyclopedia/world/characters/pippin_small.jpg for me
Puck: I... will probably choose this one. But that image always makes me a little uncomfortable. Just such a gross, un-Puck like expression.
Rakshas:Yep.
Rochine Nah, having her in her human form doesn't really work for the purposes of this. Should be in her apostle form, just not fully transformed.
Schierke: This one really captures her well. My first choice was this though:
http://www.skullknight.net/encyclopedia/world/characters/schierke_small.jpgSerpico: I think this one's a little too uncharacteristically cool to define Serpico.
Sonia: Yep.
Zodd: I prefer
http://www.skullknight.net/encyclopedia/world/characters/zodd.jpg for the emotion that it captures for Zodd.