i think electroneum is the most promissing at the moment. Everybody (even at etoro) is talking about them and their approach to target mobile users is a pretty good strategy. I don't know if they're the most promising longtime-investment but at the moment they should generate the highest profits in my opinion
do you have a link ? didn't heard about it before.
Electroneum has pretty much been doing a huge job behind the scenes as well as some pretty good marketing which makes me so eager to see how this turns out. I just downloaded their mobile app recently to see how the whole mobile mining will turn out to be anyway. Nothing is not worth trying these days and you may be surprised with the whole lot of hype going on with the project.