SMAP - if you can get over their horrible vocals, then go for it. LOL. it took me a while to like their stuff because i think out of all JE, they're the worst vocally. but the music is pretty good. lots of artists have worked for them: Suga Shikao, Nakata Yasutaka, Eric Clapton, MONKEY MAJIK, & Katori Shingo has collaborated with Koda Kumi.
TOKIO - i recommend. Nagase's voice is unique though. kinda like hitomi....but....obviously more manlier. LOL. i start out with their "Harvest" album. i'm only more familiar with their recent stuff, like year 2000 works & onwards~ BUT THEY'RE AMAZING LIVE.