B'z (Karen mentioned them already. I'd recommend starting off with GREEN, since that's the most ayu-ish album other than MAGIC and C'mon, and LOOSE.)
Koshi Inaba (Shian is a very angsty album to start off and Koshi's most raw album up to date! <3)
X-JAPAN
Porno Graffitti (Their stuff is mostly pop. But, they come up with some pretty catchy music!
)
VAMPS