I think ICO started to increase day after day and people started to trust it,The future will goes to ICO, maybe because the low price or the new features which it provides.
This is an old post but I still wish to air my view. As of early 2019 ICO started dropping badly that is, the level at which people give attention to them dropped badly and the attention was channelled to IEO and ever since then IEO took over. Also, it even got to a point that most projects already preparing for ICO had to drop the idea and move over to IEO. Lastly, the era of ICOs are gone and a lot of lessons learnt too.