IEO now has so many good bounty campaigns and you can earn from them
IEO have no guarantee of success. Some teams participate in the IEO after the failed ICO 2017-2018. The only plus is the authority of the exchange, they have to choose the project themselves for publication and it's reputation at stake.
However, most projects that run on the exchanges witu IEO, especially from the top 10, in one form or another, succeed and collect their target amounts.
I think that the programs of such projects are preferable.