You will earn more if you participate in the ICO pre-sale, because you will be able to buy tokens up to 20 - 50% cheaper and then sell them after the ICO.
Regarding good ICOs, has anyone heard about menlo.one? They're an ICO review platform and marketplace launching their token sale this July. Do you think this project has potential? Their white papers seems interesting to me
https://www.menlo.one/