IMO Bosh spends at least half of his time at C. Whenever Nesterovic is not in the game Bosh is the center. According to 82 the second most utilized 5 man unit for the raptors last year included Bosh at Center. He also played center in 4 of the top 10 units:

Rotoworld lists Bosh as a F/C:

As does Yahoo:


The two other players in Toronto's big man rotation are Bargnani and Garbajosa. Both are listed on the player pages as F only:

Bargnani's game is definetly not that of a center although he is tall. And Garbajosa has been mentioned as a possible starter at SF.