CustomShow is an industry giant and the default software for developing presentations for the projects and important tasks. The biggest thing of CustomShow is user friendliness and ease of use. There are per-set themes that come with it but are easily manipulated to better suite your presentation. CustomShow is an excellent tool which provide lot of features for animating, designing layouts, editing, quality and stability of presentation.

I like that the background templates are interactive

It provides sharing capabilities, is cloud-based, can be used to truly customize presentations, helps with branding, integrates video incredibly well, and imports old powerpoints into the software. It is incredibly useful with also viewing statistics on how prior presentations well. I think it's slide library is its best feature.