Just choose a block well in the future and let the market sort it out. People who want to buy or sell before the cutoff will do so. People who want to wait until after and just buy or sell one of the coins can do that. That is completely fair to everyone. No one gets any particular potential advantage from the choice of the block.
Any solution which doesn't allow anyone to do insider trading is "fair". In this case we trust that dooglus didn't do it, supposedly the only one knowing about the screenshot. But looking at Poloniex volume nothing strange seems happened.
A snapshot in the future could be maybe "fairer", but it will lead to quite a price turmoil, with a possible bubble where many people will end up making poor trading decisions and losing money. This is already quite bad when nobody wants it, but looking actively for it seems like pushing the gas toward a wall.