RE: In your opinion, which "new" cryptocurrency will become very big and why?
Many can succeed, Dash is my favorite. Evan Duffield stepped down from the Dash Core team. He's in more of an advisory role as far as that is concerned. He started up Dash Labs to start working on future-proofing with scaling and large scale adoption.
“I myself will be heading up the new office in Hong Kong, called “Dash Labs.” We will immediately begin building proof-of-concepts of custom masternode hardware. Our existing offices in Arizona will be used for academic research. This research will be aimed at proving our ideas work and proactively searching for any problems before they crop up.”
Source
I also like Monero as being successful, but I don't think the use case will be as strong. Dash is more for day-to-day use and Monero is if you don't want a trail. Kind of like the people who use a Debit card for everything vs. the people who use cash for everything. Both are useful.