PFC flyback LED driver comparison, fixed frequency or variable frequency is best?

[treez]

LM3477 is an offline fixed frequency critical conduction mode flyback controller
LT3799 is an offline variable frequency critical conduction mode flyback controller.

Which gives the best PFC? (fixed or variable frequency?)

LT3799
http://cds.linear.com/docs/en/datasheet/3799fa.pdf

LM3477
http://www.ti.com/lit/ds/symlink/lm3447.pdf