Which platforms for startups and/or ICO are the most popular nowadays?
Thanks
Ripple hasn't taken off but has the backing of a lot of major corporations.
Here's some background on it:
https://ripple.com/Be careful investing in ICOs, most of them are rubbish. Seriously, most don't offer any evolution or new feature that makes their cryptocurrency better than Bitcoin, Litecoin, etc. If the coin isn't offering something better than Bitcoin it's not worth your investment.
Do your own research. Make your own decisions.