Too difficult to choose the best one, I mean there is no one that gives teh real product for the users. All of them have the same chance to be success in the future, But not until the real product gets roll over.
Product = proof if the project already successful
It will be even more difficult. Check this site out...
https://www.icoalert.com/TOP 5 ETH Tokens ROI since ICO:
1. Etheroll +9731.01%
2. Golem +3720.22%
3. Augur +3707.18%
4. Swarm City +2861.73%
5. Iconomi +2278.65%
BOTTOM 5 ETH Tokens ROI since ICO:
1. Bancor -36.94%
2. Cofound.it +13.45%
3. Status +14.12%
4. TokenCard +30.57%
5. Blockchain Capitol +44.26%
These were gathered from
https://icostats.com/roi-since-ico