Because betking is having 6,377 bitcoins in their bankroll your share will be only 0,00784%, means you'll have tiny profits.
share at cryptogames.net (979 bitcoin bankroll) will be 0,051%, share at moneypot (738 bitcoin bankroll) will be 0,0677%.
Since moneypot is not profitable for a long time, i wouldn't invest there, leaving you a chance between cryptogames and betking. Cryptogames is having lower house edge on dice than betking, but is having higher on other games and giving you higher percentage in bankroll.
It's also explained in this post: http://bitcoingamblingreviews.com/bitcoin-gambling-investments-212/
Based on that i would choose cryptogames