Thinking over the current meme, my five favorite on-going manga series would probably be, in no particular order,
1) Hot Gimmick, due to its cast of likable characters, and an absolutely ravishing character-design style, for which my admiration only grows with time and familiarity. I just love that non-continuous, razored-line eye work. The soap-opera story is still working, too, although the author is getting very close to the end of her narrative rope on the main relationship by the end of the current volume - she needs to let it resolve, I think. It's not as if she can throw another violent sociopath or contrived recovered-memory trauma at the main couple every other volume, like the author of Mars did.
2) Bleach, which is just another disguised-sentai psychic-teen actioner, so I really ought to be ashamed of loving it as much as I do. But really - it's an *excellent* psychic-teens punch-em-up, with a fine sense of style, and some of the funniest, cleverest facial expressions in manga. It's built of nothing but cliche, situation, and stock-character - but the execution is so brilliant that I can't do anything other than gush.
3) Tramps Like Us, aka Kimi wa Pet, is a bit of a rarity in the manga released in the states, in that the characters are all actual, living, breathing adults. Nothing much ever really happens, but the nothing that happens just makes me happy.
4) Please Save My Earth just keeps cranking along, and it's definitely one of the series which I await, impatiently at best, every other month for the latest installment. I'm especially excited now that the story has gotten past the parts animated in the early-Nineties six-part OAV series. I can only hope that it's more Rin-and-Alice than Tamura and the rest of the stonefaces.
5) XXXholic, for the chill, stark black-and-white imagery, and Yuko, 'cause she's just cool. But Del Rey is *not* helping me keep to this love with the fourth volume's scanned-at-one-level-too-coarse ham-handed presentation. I don't care how expert the line-work is coming from the artists, if the production-line squiggles it all to pixelized mush. Damnit.
On the other end of the scale, I grabbed a few things from the Comic Swap's bargain-bin the other week, and found myself marching through Dark Horse's Club 9, which wasn't exactly attractive at $15.95, but was worth a whirl at half-price. I say marching, because it was something of a slog. There have been a number of folks talking up Club 9, but I can't see for the life of me why they would have done so, barring a knife at their collective throats, or some malicious urge to direct unwary readers towards experiences of pain and irritation.
Club 9 is a slice-of-life-sorta story about a north-country Japanese hick's young-adult life as she graduates from high school and goes off to college in Tokyo. Our protagonist Haruo is ugly, dim, unlucky, a klutz, and burdened with the worst accent since the days of Ma and Pa Kettle. Seriously, the translators make her sound like the sort of imaginary, stereotypical, inbred hillbilly that haunt the dreams of election-burned snobs all up and down the blue-state coasts. She uses idiot country similes too insane for Dan Rather, and drawls like a coke-addled Yazoo County beauty-pageant runner-up. It wouldn't be quite so bad if they were going the hush-mah-mauf sly-hick making fun of the snobs comedy route, but they aren't. We're supposed to find her endearingly naive and lovable in her stupidity. Hell, we don't even get to the titular Ginza hostess-bar setting until the back third of the first volume. Instead we have a tedious meander through baseball politics and the horrors of dorm-room hauntings and such.
It isn't as if the manga is particularly enjoyable to look at - the layouts are uninspired, and the character designs are like the retarded cousins of those early-Meiji woodcuts of cross-eyed, jellybean-faced galloots that get trotted out whenever an editor wants some offensive graphics to accompany something borderline racist and stereotypical about the Japanese. I could take that in a gag comic - but this is supposed to be about attractive, vivacious Ginza-bar hostesses! Bah, I say: Bah!