Expert is the most fun on those games. If you think its fun now, wait till your playing Knights of Cydonia on Expert! Its instense. Anyway, HIGHLY recommended you get rock band. I know the $170 (i think its still that price) is high, but WELL worth it. Ive spent waayyyyy more time playin drums, bass, and guitar on rock band than I've played guitar hero. Also, Rock Band guitar is, well, a LOT easier than GH3 to play.
I pretty much skipped easy, went to medium for a little while. Some tips for new players.
Dont spend time "mastering" easy and medium, these won't help you in the long run. What you wanna do is learn the "slide" on hard. This is the most useful tip right off the bat. Also, learn hammer-on notes. This will definitely help you beat the intense solos. Something I wish I would have learn right away is up-and-down strumming. I dont know about you, but my thumb was F'in tired after a couple songs that were really fast. Using up-and-down strum, you dont really get tired at all. These should help anyone learned fairly quickly. ROCK ON!!
...also have some tips for drumming if anyones interested, just about beat rock band on Expert, just havent played for awhile to complete it