Depends on what you call "popularity". Is it winning Nikkan Sports Drama Grand Prix? Is it getting high TV rating? Depending on your definition of "popularity", the answer will change. For me, TV rating is reliable, more so than online polls and Nikkan Sports, where you can get many fangirls to vote for you multiple times. That's not necessarily true popularity.
So, going with my definition of popularity, it is Kimura Takuya. None of his kouhai can manage to match him in popularity
. Even if his dorama plot line is not good, like MR. BRAIN, he still manages to get high rating.
*Edit*: If it's just young JE actors (which I generally don't like
, just because it takes men time to mature), then probably YamaPi. Regardless of whether you think he can act or not, he still has a large, consistent fanbase, and his projects are generally
decent. Interestingly enough. Nobuta wo Produce is one of my all-time favorites, and Proposal Daisakusen was a good drama, with certain flaws (the acting being one of them).
As for the acting, everyone's opinion is different; so here's my 2 cent.
most of SMAP
(except Inagaki Goro. I cannot, cannot stand his acting). I particularly like Nakai and Kusanagi. Going down the age group: Nagase Tomoya
(though I think he overacts sometimes), Ninomiya Kazunari
. These two are the most consistent.
The ones with potential but inconsistent
: Matsumoto Jun
(I think his role in HYD requires him to overact), Sakurai Sho
(I find him cute in the cutesy roles, and he doesn't seem to try too hard), Kamenashi Kazuya
(I love Shuuji, it seems like that role was made for him, but his other roles range from bland to nothing special to overacting. Plus I think with his recent drama, he's heading in the wrong direction). I kind of like Ikuta Toma
in Hana Kimi, but his other roles also gave me doubts. Nishikido Ryo
is OK, but his roles seem so similar - the emo, quiet, moody character.
The ones who don't impress: YamaPi
(I like Akira in Nobuta wo Produce though, I have to say) - but he seems like a nice person - side note, also Takizawa Hideaki
, and others.
But my favorite pick of the bunch is Okada Junichi
His dramas (to be precise, his most important ones are probably Kisarazu Cat's Eyes
, Tiger & Dragon
, and SP
) are not the most popular, especially among non-Japanese viewers - they don't target an audience of teenage girls. Also, V6 is not the most popular JE group (or anywhere near the top popular), and he has shifted his focus to films rather than TV series, etc. Those are a few reasons why he might not be widely known despite his fine acting.
What impresses me the most is that though he has very few dorama projects, all of them have been decent, and he never repeats himself or acts the same way in more than one role. But then, I really do think though he's good in his dorama, he truly shines in his movies - Tokyo Tower, Hana yori mo naho, Kage hinata ni saku, and the latest Oto-na-ri. Doesn't overact, has expressive eye contact, and very versatile.
One final note
: actors who can't act are very abundant. They're everywhere, not just JE. The only difference is that JE has a lot of power, so their so-called actors flood the screen every season. As much as I hate the influence JE has, and only care about 1 person in the entire JE clan (kind of obvious from my post who it is haha), I find it funny that a lot of people judge that someone can't act just because he is a JE boy. Personally, even with people I dislike, I try to give them a chance if their drama/movie sounds promising enough. Even if they can't act, there might just be a role that's right for them (Akira in Nobuta wo Produce for example). So, watch before you judge.