i don't pay a lot of attention to seiyuu, though i do like nana mizuki's singing & i liked her in the roles i saw her in!
as for an archetype... oblivious cutesy bright-eyed kids who make everyone's life better without even realizing it by being just honestly good people. also, in reverse, complete and utter total assholes who manipulate people and set up drama for fun. i'm a little on the ends of the spectrums there. :p