I don't know who I like the BEST. I like all of them in the following order: Tsuyoshi, Nakai, Goro, Kimura, Shingo (at least this is the order right now, before it was Kimura, Goro, Tsuyoshi, Nakai, Shingo, then it was Tsuyoshi, Kimura, Goro, Nakai, Shingo, then to Tsuyoshi, Nakai, Kimura, Goro, Shingo).
I have watched a few of their concerts and even though they tend to sing many old songs over and over, I can never get tired of hearing them sing the same songs and seeing them perform the same dance moves. Also it is really nice to see how they do different renditions. Some of the fast songs, they will sing them either acoustic version or a slow version of it. Which I think keeps it quite interesting. Also, I like when they do medlies, and the medlies will have a music style theme to it (example: in Drink Smap concert, they did a Samba theme to the medley, this is early in the concert and they dance Spanish style -- that was cool). In their 2000 concert, they did a Disco theme and a Mission Impossible theme.
In some of their concerts, I like how they will take some American songs and the lyrics are replaced with Japanese lyrics. Also, the dance moves are always very hot.
In my opinion, I feel Kimura is the best dancer, followed by Nakai, Tsuyoshi, Goro, Shingo.
In terms of acting, Tsuyoshi is the best actor of the group, followed by Kimura, then Nakai. (I am recently watching "Suna No Itsuwa", wow!!! Nakai is so impressive in this, his acting is amazing. I have not finished watching it, but so far it is really good and intense. After I finish it, I think I may change my opinion about who the best actor of the group is... but then again, I am very heavily influenced by Tsuyoshi because I have watched him in nearly everything he has appeared in.)
Singing -- Kimura is the best, followed by Goro, Tsuyoshi, Shingo, Nakai.
Each member of Smap is special in their own way and each have their own talents.
I really enjoy watching Smap in concerts, tv shows, dramas, movies, music videos (clips). I just cannot get enough of Smap.