Snark king SIMON rates past Idol champs & reveals his favorite singers!

As the excitement builds on Simon Cowell’s last season with American Idol, the judge who’s been dubbed "Mr. Nasty" takes  a look back at the hit show’s eight winners.

In an exclusive ENQUIRER interview, Simon – who’s leaving AI to launch an American version of his blockbuster British talent competition The X Factor – names his top picks.

The tart-tongued music genius didn’t mince words as he shared what he REALLY thought of past champions.

And – dare we say it – snarky Simon got downright sentimental at times!

To find out WHO Simon’s favorite Idol contestants of all time are – pick up the new ENQUIRER – on sale now.