KHL is the best non-NHL league. The veterans in the AHL are just as good and can make just as much, but the status as a developmental league brings down the AHL a good bit as you have a lot of not that good players being put into lineups and bigger roles than merit would have it because the parent club wants to develop them.
SHL pays a lot less than KHL. It's a bit closer with the Swedish and Finnish guys leaving the KHL, but the KHL attracts a much better and much larger contingent of Canadian players, and the Russian guys are less likely to leave the KHL for other non-NHL leagues (and the lack of a transfer agreement leaves a lot of Russian guys in the KHL longer/more permanently even if more borderline NHL).
The other "X" Factor is how much higher quality of player Belarus is producing in recent years. This is offsetting the loss of Finns somewhat.