Best Fun Factor class ... I would say crat or adventurer - they have a lot of nanos and fighting monsters is pretty different compared to other classes, "I wonder if i can charm this monster", 10 secs later "Iek! i wonder if i can calm it." "iek iek. lets hope this root works.."
duelling non-rooters/calmers is also fun, just sneak and do /pet attack :P
Adventurers also have a lot of funny nanos + they allow to wear almost every weapon selfbuffed (at highlvl)... (nova, flashpoint, hammer, beam, eqb, whatever) ...
and hey - most important: noone will beg for a wrangle or maestro while playing these toons :P