Liiga is likely not better then the AHL.
Players generally retain far more scoring moving from the AHL to the NHL then they do from the Liiga.
obviously not a be all end all assessment, but i dont' know how else you would objectively determine which is "better".
obviously there's stylistic differences due to big ice, but those would exist in the SHL as well which carries over more scoring then the AHL does (as far as NHLE's)
SHL= .6
AHL= .47
LIIGA = .29
again not a be all end all, but i don't think you could equivocally claim the Liiga is better for two main reasons
1) the above NHLE conversions
2) Pool of talent. The AHL draws talent from across the globe, many of which are pegged to be "the next ones" in the NHL, where the Liga has far a less of a global reach. No Canadians/Americans/russians/etc with NHL potential are going to go play for Liiga teams. On the other hand, players from anywhere in the world with borderline NHL talent DO play in the AHL.
again, it's a subjective thing, but it's highly unlikely IMO that the liiga is "better" given the above.