They are both good but i refer now to IEO it has exchanger already that after the duration of IEO once it open on trade we can sell tokens,while ICOwe need to wait until they list on exchangers and we dont know what exchanger they will list it sometimes they list on a cheap Exchanges so at the end tokens dump.
It is difficult to find a good ICO like in 2017, most investors divert investment in the IEO, this is because it is safer and verification of exchanges is certainly stricter than ICO which has no verification.
whether the crypto project to be launched in the IEO will be analyzed first by the management market before they are allowed to presale the IEO on a market exchange? or only by paying a certain amount they are immediately accepted to open the IEO presale on the website market?