Augur is the only ICO I still hear a lot about in terms of having an actually useful purpose (beyond the market surrounding the coin itself). So this should be at least one correct answer to OP's question.
Disclaimer: Have never used it myself.
I've used it and it's fairly straight forward if you're tech savy. I bet on the midterm election, and the price of ETH. Since it's just a set of smart contracts, I expect market makers to start building 3rd party UI's to shill their markets, which should be interesting.