I've been a fan of Arashi for more than 10 years, since I was in HS. So, when you ask me, way back 10 years ago, "Who is my ARASHI ICHIBAN?", I would consistently answered it with "MATSUMOTO JUN".
Why? First of all, he's the first member that I have known in their Jpop Group named Arashi, since I have watched him in the First season of GOKUSEN. He is totally handsome, an Ideal BF (*giggles*).
Second, he's damn so hot(hahaha!). Yeah, I've seen already his Marie Claire Cover Photo in the Internet(sad to say, I wasn't able to save one photo that time because, you know, I'm only 14 that time to have that kind of photo,and PARENTAL GUIDANCE IS STRICTLY ADVISED..XD). I admit, he's kinda skinny that time, but, GOSH, the way he looks to the camera,HE'S HOT (just nevermind the body.LOL!). XD

But,as time goes by,wherein my fandom level already turns into a Up-Down-Up momment, I've already seen Arashi's different characteristics, which make me love them more,individually and by group. I have noticed each kindness of the members and each abilities, which gives me an headache already everytime I meet other Arashi Fan in GC or in person, asking, "WHO'S YOUR ARASHI ICHIBAN".Like now, I like AIBA MASAKI because of his cute BAKANESS and his HOT aura (esp. In Kizuko Tantei,hihi). In the other day, I like NINOMIYA KAZUNARI beacause of his AGELESS FACE and his cute BRATTY character, especially his month is already approaching(ehem, JUNE! XD). In the next day, I like SHO SAKURAI because he is REALLY SMART and being FUNNY HANDSOME CHIPMUNK. And next day is OHNO SATOSHI because of his BEAUTIFUL VOICE(although in variety shows, he is rarely hear and see him talking before), GREAT DANCE MOVES and his FUNNY PUNCHLINES (especially in VS ARASHI and ARASHI NI SHIYAGARE).

So,now, when people ask me the same question again and again, eventhough I always answer it with, "MATSUMOTO JUN", there is always a follow up sentence, "BUT, IT STILL,DEPENDS ON THE MOOD".

That's for now! Have a nice day minna! =)