I dont know what the best multi-role fighter is any more. I think it's quite mission specific any more. The F-18 has certainly proven it's value as a close support multi role fighter, as has the F-16, but then so has the J-10 from the PRC, and the SU-27 from Russia, and the Tornado from Great Britain. I dont fell that the F-15 is multi-role as it's design is air superiority
The F-16, F-18 and SU-27 are pretty even in my opinion, and the tornado is ex-calibre as it can span so many seperate roles and do them equally well..
The F-18s lack of range seems to be it's only weak spot, The F-16 is simply getting old as is the SU-27 and J-10.
The J-12 from the PRC enters service on May 20th of this year, and with the armament load plus maneuvering capabilities it has, i can only come to the conclusion that for at least a couple weeks of time, this plane is going o be the most capable multi-role fighter in the world..
Pam