Even though I play a lot of online poker, I chose Lottery.
All the other games are pretty well represented online with fairly high 'trust' ratings, so there's not that much advantage to having them as DAC's. Having said that, as the crypto-economy grows, being the leading poker/bingo/casino DAC will still be very lucrative.
The lottery DAC on the other hand can double the average players winning odds because of the 50% waste in the current centralised real world model, so there's a real opportunity there to be a really disruptive game-changing, excuse the pun DAC IMO.
Edit: Another advantage is that our crypto-currencies are borderless, so the long term potential is that the leading lottery could ultimately become a global lottery - much bigger than any current lottery - being able to offer bigger prizes at much better odds is something real world counterparts could never compete with.