The majority of my projects have been Tamiya 1:12 bikes... All Rossi replicas. In my stash at the moment I've got his Fiat Yamaha M1 from '09 and the RCV211 Valencia special. Can't wait to get my hands on them as I've never had a problem in the past, except my early days, when my modelling skills were limited to a paint brush, some scissors and a dab of glue.
From memory, my favourite kit so far was the 50th anniversary in red, white and black (pictured). Going by this, my opinion is the later the model, the better the quality.