strongest player to never become official world champion

Keres and Korchnoi are the obvious choices, but I feel like there's probably somebody from Kasparov's run of dominance who would have been world champion if not for Kasparov.

Ivanchuk, Short, Beliavsky, Timman, Gelfand - one of those guys. Probably Ivanchuk.

Leko was very close.

Akiba Rubinstein

Schlechter, Rubinstein, Bronstein, Keres, Larsen, Korchnoi, Kamsky, Leko, Lovlas

One of those are not like the others.

True lovlas, Bronstein is the only one whois name starts with "B".

Pillsbury