If I choose, I prefer IEO than ICO. IEO is more trustworthy because they do crowdsale on the exchanges. While ICO only do crowdsale on their platform, I think it's possible they will be scam. I remember when I first bought coin lending on ICO, they just disappeared without any news. I lost a lot of money at that time.
With an ICO, we have to do a thorough research. because ICO is very vulnerable to scam and also other things related to it. different from ICO, IEO is more reliable and also safe. You only need to look at the IEO platform or exchange to be able to determine a good IEO, so IEO is better in my opinion