If the indicator is investor interest, I believe that IEO is better than ICO. Moreover, lately many ICOs have been a scam, not being listed on the market even though a lot of time has passed. That is why the IEO strategy is more in demand by investors today. However, it also does not guarantee that all IEOs will succeed. It depends on many things, such as exchange, market interest, project strength, marketing strategies, etc.
I agree that recently in the crypto market there are a lot of scammers among ICO. However, there were better times when the right ICOs made huge profits, which none of the current IEOs can compare with. And all investors of such ICOs made a lot of money. And I really miss those days.