I am not recommending per se, since I use scanlations to find out which series are worth my moola. Ironically, at the end of the day, I do buy most of the mangas I am reading...
Well in no order of preference, these are the series I am actively pursuing (i.e. I ask whether the latest volume is out when I drop by the comic shop):
1) Ichigo 100%. (its 草莓 100% (in chinese) and translated and published by Taiwanese publishers Boys if you do read chinese. I guess you can call it 'not popular' since no Hong Kong publisher has picked it up yet... heh)
2) 20th Century Boys. (Excellent. But, pales a bit in comparison to the tight storyline of Monster. Then again, alot of manga out there pales in comparison to Monster...
)
3) Eyeshield 21. (unique, since no one has ever done a sports manga on American Football, of all things...
)
4) Magister Negi Magi. (er, light reading. )
5) Yakitate Japan. (I guess everyone knows about this.)
Merely 'collecting' mode (some originate from waay back before there were scanners and scanlations):
6) Guyver (a cookie to those who remember this series...)
7) Bastard! (I heard volume 23 is out, again, another slow one)
8) Berserk (yeah, another very slow one)
9) Ah! Megami-sama (not stalled, just has no end in sight)
Some of the new stuff that has just appeared. (as in around 5 volumes...)
10) Tsubasa (by CLAMP. Before you cringe, it features a romp through the CLAMP universe...)
11) Deathnote (Plenty of dialouge. Chinese may be my mother tongue but even then it got me lost plenty of times)