For me IEO is a better than simple listing but we cant compare much for these two. In IEO token or project has been display or promoted by the exchange showing its strenght by displaying their tough platform. Simply like Binance completely presenting their project worldwide and the demand is highly appreciated. But for direct listing, we can also see good news with it. See how solana pump even though its not an IEO but only for listing. I can say on other exchange IEOs are not working efficiently but based on my statement on big exchange IEO is much appreciated and highly effective. But its your own opinion to believe me or not.