Success factor is dependent on project vision. What makes one project succeed might not work for another. Different projects different success story especially when there's competition in the market.
I think ico now can not collect even the soft cap , and it is unlikely that ever ico will already collect large funds, it is better to give preference to ieo.
Switching to use IEO as a fundraiser could be a good option to go with since some peoples find it hard to directly trust the project themselves. Its not that there is much like a major difference between ICO and IEO but I think scammers operating behind a project has somehow played a role in IEO's success.
Right now there are very less people who still like to invest through ICO's and its for the best when we are dealing in crypto world.