My best choice would be bitcoin as it was the pioneer of all them coins and the prices would definitely pump up in the near future. My 2nd best choices are dash and eth. Most widely used coin for ICO today is Eth so it's a good indication.
For the time being, the Bitcoin is the best. but it will change if the network is still very congested.
Bitcoin should be the best coin but the fork in a row made the bitcoin is very risky. As you can see there will be next hardfork to the bticoin and that will be issued the bitcoin gold as the resulf of the hardfork.