Hmm...well Aki and Janne have their own styles and unique features and The Rasmus would never have been without either of them.
but...
Janne was around when the band started - therefore he was one of the members who actually made Rasmus (as they were then) Rasmus and lead the others to choose a different drummer when he left the band to search for peace within himself.
Aki is a more popular drummer not only because his drumming has a more distinctive effect of the songs TR make now-a-days but also because TR became more widely known world-wide when he was in the band...
difficult question - needs more thought me thinks
