Honestly, it's all just speculation lol. I'll be happy with whoever turns up.
I love T&C. They're a mishmash of non-idols becoming idols and being really fucking awesome at it. I mean, RuRu wasn't anything, Inaba was part of a performance group, Miho was a rhythmic gymnast and Miwa was an enka singer. But they worked together. They were all super talented and their songs were all amazing and they were such a perfect group and I love them all so much and I'm really sad they didn't last longer. They're one of my fave H!P groups tbh.
Melon Kinenbi are also pretty neat. I don't love all their stuff, but they have some amazing songs. Like This is Unmei. Which is one of my favourite H!P songs. (And other ones.) Also, Saitou Hitomi. They have her.
And I know Country Musume。weren't, like, super amazing or anything but they have a special place in my heart. I'm not even talking about the lineups with Morning Musume。members (even though Country Musume。ni Konno to Fujimoto was the best). I would have really really loved the original lineup if it... didn't fall apart. Yanagihara Hiromi was super cute from the few pictures we have of her, and it's a shame she died. And then there's Rinne and... I love Rinne. So much.
I also love Coconuts Musume。even though they weren't that great.
Oh, and Sheki-Dol. But nobody really knows Sheki-Dol.
I'm sorry I really like a lot of the oldschool H!P groups. Of course, I do like the current ones more, but these ones are still pretty fucking neat.