Risa's "ai iro no kankei / tamote nakatta mitai SAYONARA" in the last chorus of Indigo Blue Love
Eri's "bikini ni yottopaakaa" in Purple Wind
Kago and Tsuji's "EVERYBODY SCREAM!" in The Peace
Konkon's "hare wataru kara" in Ambitious!
Tsuji's "zutto akogareteta hito to saikai shita" in Ai no Sono
Mari's "pa pa pala no ACHAA!" in Happy Summer Wedding
Yossie's "so sore DANSHINGU natsu matsuri! wasshoi!" in Dancing! Natsu Matsuri
Risako's "Hmm/Mmm~ yes my love!" in Munasawagi Scarlet
Risako's "mune ga itai" in Kokuhaku no Funsui Hiroba
Risako's "hoppe ni kissu shite" in Toshoshitsu Taiki
Miyabi's "watashi PIERO" in Kokuhaku no Funsui Hiroba
Pretty much all of Chinami's lines in Semi
Chinami's "no nyu! no nyu!" in Gag 100kai bun Aishite Kudasai
Yurina's "yume yume de do up"s Yume de Do Up
Yurina's last "deau no kamo shirenai" in Natsu Remember You
Megumi's "fuan ni omottari suru wa" in ENDLESS LOVE ~I Love You More~
Megumi's "aitai" in Shiroi Tokyo
Maimi's "yasumi no hiniwakurumade" in Yes! Shiawase
Erika's "waza to samusou na shigusa wo shitara" in Shiroi Tokyo
Aaaand I'm going to stop now before I go WAY overboard.
And as for the line pwners, while they're not too well-represented on the ones I picked, I really think that
Risa, Tsuji, Chinami, and Miyabi are my picks. Risa is absolutely my favorite live singer in all of H!P-- she always sounds amazing on her lines, simply put. Tsuji... I can't explain it so well. ^^;; Whenever her lines come up in a song, I just love how she handles them. Her voice always works well with the lines she's given-- whether it's really, simple small things like her solo line in All for One & One for All, or the longer line I mentioned in Ai no Sono, and always sounds really good. Chinami's another one whose voice I just love; while she doesn't get nearly as many lines in singles as the main singers of Berryz do, she always pwns what she does get there, pwns the b-sides she's in, pwns album songs-- everything.
And what I like about Miyabi is that not only does she pwn her own lines (in specifically Berryz songs), she pwns OTHER people's lines. What came to mind instantly once I picked Miyabi was her lines in 'Hare Ame Nochi Suki' in the 2007 H!P winter concert. While almost all the others seemed pretty shaky, Miyabi just comes in with such confidence and pwns them all. Quick link to the performance is here--
http://www.veoh.com/videos/v359264Sd3MYXcj if anyone wants to see; I really think that's my favorite Miyabi performance EVAR.