I'm observing Byteball and have read the whitepaper. I'm not sure if the DAG has any advantage over a traditional blockchain besides faster transaction propagation, so that could be a plus.

But on the other hand, the coin is actually very centralized (it can be regarded as a "proof of concept" at most) and not totally trustless, even when the witnesses are to be freely elected it will be more a kind of "web of trust" like Ripple. I regard it as more centralized - and thus more vulnerable to social engineering attacks - than DPOS coins like Bitshares.