Well, so here goes my first thread 
The title is self-explainatory, just mention your favorite and least favorite MV from each major H!P group you have ever followed. I don't think there's a thread like this and I'm curious about everyone's choices hehe. If you want, you can explain why you love or dislike the MVs you listed, but it's also fine if you don't.
So this is my list
Berryz Kobo:
Favorite: Hm, there are a lot Berryz MVs I love but I think my favorite one is cha cha SING; I love the song, I love the outfits, the choreography is simple but it makes you want to dance along, the setting wasn't super flashy or anything, just some colorful curtains decorating the walls, but that was enough for that PV (in this case, less is more indeed), the girls looked great, and most importantly: THEY WERE HAVING FUN. One of Berryz' strong points was their personalities and cha cha SING shows that perfectly. I never ever will get tired of that song and MV.
Least favorite: Golden Chinatown. I mean, I really like Golden Chinatown as a song... but my goodness, that's (sadly) honestly one of the worst music videos H!P has ever made, and definitely Berryz' worst. It's just formulaic to death 
Ooh, I have so many ideas on what else could have been done with that PV so I can't comprehend how they couldn't think of something, ANYTHING, interesting when there's so much you can do with the chinese/oriental motif. I so prefer the dance shot (I actually like the choreography quite a lot) over the actual PV. At least that's interesting to watch.
°C-ute:
Favorite: Hmm... Most likely Kanashiki Amefuri, I'm not the biggest fan of some of the dance moves... but everything else about the PV is great, I love all the things that are going on in that one, it was a very well made MV.
Least Favorite: Uh... I wonder... FOREVER LOVE, perhaps? Now, don't take me wrong, FOREVER LOVE is an amazing song and one of my favorites from °C-ute and I LOVE the choreography but the MV itself looked quite cheap and was also quite formulaic outside of the change from the casual clothes to the black suits. Same as with Golden Chinatown, I prefer the dance shot (shots in this case) to the actual PV.
ANGERME:
Favorite: Mahou Tsukai Sally hands down! 
Okay, so I havent' seen all of S/mileage/ANGERME's MVs yet because it wasn't until recently that I became more interested in this group, but I'd be really surprised if they have another MV better than this one, the only MV that comes pretty close to MTS for me is Dot Bikini but I think I overall like Mahou Tsukai Sally a little better. Fun and catchy song? Check. Cute and colorful outfits? Check. Nice setting? Check. Fun choreography? Check. EVERYTHING ABOUT THIS MV IS FUN.
Least Favorite: Uh... I don't know, maybe Tsugitsugi Zokuzoku's? That wasn't necessarily a bad PV (because the girls looked great and I had fun watching it) and I like the song but... yeah. I guess it's the he seetting that was just meh (and why those glowing sticks coming out from the floor' lol)
Juice=Juice
Favorite: Kaze ni Fukarete. I love how soft and dreamy the MV looks, the girls look great, I like the choreography and the mini-story was nice too.
Least Favorite: Watashi ga Iu Mae ni Dakishimenakya ne... I mean, it's their most plain MV, it's not really bad, just plain. I'm happy just watching the dance shot because I love the choreography.
Tsubaki Factory:
Favorite: Aaah! I don't know which one to pick Hatsukoi Sunrise or Uruwashi no Camellia? Uruwashi... no wait, Hatsukoi Sunrise! Or maybe it's Uruwashi... I can't decide! ...*shivering* Well, since I love everything fun and cute, then maybe I loved Uruwashi no Camellia a little more so... that... one... It's just so nice to see the girls have fun.
Least Favorite: Seishun Manmannaka! for sure. I really like that song and the setting was nice and the outfits too but who thought it'd be fun or interesting enough to watch the girls just sit there lip-synching to the song? There's not even a dance shot (no, those random bits of a live performance don't count, plus they look quite out of place). The brief close-up shots don't spice things up much either... It's the formulaic curse again! 
Kobushi Factory:
Favorite: Kobushi no Hana. I think all of us were impressed by this PV. Someone just give the director an award, please! 
A beautiful PV for a beautiful song 
'nuff said.
Least Favorite: Samba! Kobushi Janeiro... The song is good and the PV isn't really bad or anything but I just feel so awkward watching those women in such skimpy clothing... 
I know it adds to the whole Brazilian theme/mood but to me, those random women just spoiled the MV 
Country Girls:
Favorite: Ack! This is tough... *sigh* I've loved a lot of their PVs so far but since I have to choose only one... Okay, Ran Ra Run Anata ni Muchuu was really good, I love love love the setting and the cute mini-story going on 
it's so funny to see Nanami, Musubu and Mai dressed as gentlemen 
Everything about that PV is so precious 
Least Favorite: Aw, Country Girls so far hasn't had any PV I disliked (thankfully) but I guess the PV I loved the least was Koi Dorobo... The PV is pink and cute but I guess it's their most formulaic PV... so that's why I'd say it's my least favorite PV from them right now.
Buono!
Favorite: Buono! too has a lot of great music videos but I especially love Hatsukoi Cider's. I love those pink suits (Momo and Miya looked especially great in that PV), I liked the little implementation of the green screen, I like those shots from below, the setting was nice, I love when Buono! has a live band... It was a creative MV IMO
Least Favorite: Ren'ai♥Rider. It's just that silly idea of making the girls ride on miniature bikes (a tri-cycle in Momo's case...*facepalm*) because everything else was pretty ok.
Melon Kinenbi
Favorite: Namida no Taiyou. I just like those facial... stickers? (IDK, right now I can't think of a better word for those cool tear-thingies they have on their faces in this MV ), heh, that and other things about this MV kinda reminded me of Heroine ni Narou ka! and I love that MV, I also liked how sparkly this MV is, and all in all, I thought the girls looked really cool, plus I love the song.
Least Favorite: Amai Anata no Aji. I don't really remember much of this MV (lol), but I saw it once and I remember the styling was terrible among other disasters... Poor Melon for having such an awkward debut single... It is bad when I cannot remember more of the PV other than it was VERY awkward, right?
Morning Musume
Favorite: Toki wo Koe Sora no Koe. The first time I saw this PV I immediately thought of "Ryuusei Boy's Blue Version" lol... But Toki wo Koe Sora no Koe has a really pretty MV, that is all 
. I still have a lot of MM MVs to discover given that I don't really follow them but right now I think that is my favorite MV from them.
Least Favorite: Ah, I'm sure this isn't their worst MV and I really like this song but that futuristic motif they used in Ren'ai Revolution 21 felt so awkward... the 90's have passed lol. The MV just doesn't age well IMO,
Also I love Summer Wind a lot as well)
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