The answer to this is simply and straight forward. IEO is better than ICO or STO. IEO introduced a more realiable quality to crypto crowdfunding. With IEO, investors know the exact amount of the coin or token been distributed or purchased and also know the progress of the project in relation with the amount of the coin or tokens been sold at a particular moment in time. But With ICO, not all transaction info will be made available for investors and the general public to know. IEO represents true transparency rather than ICO or STO..