I've been looking for timeline programs and haven't found many that really satisfy me. Most of them restrict you to powerpoint-like slides or don't allow for very complex date or period indication. I'm currently using time graphics, but it's only effective if you pay for, what I find to be, an expensive subscription. I'd love to hear what professional historians use to create their digital timelines!
Depends on your goal. I use Timeline.js, https://timeline.knightlab.com , for timelines in my classes and for interactive online display. If I need to make one from scratch for a dead-tree pub, I use Adobe Illustrator.
I use Cliovis @ Cliovis.org. My students can collaborate with the platform and even present. It's easier than timeline js. You create a project, the students join it and build timelines from there. Or, if you are only using it for yourself --that works too. Happy to tell you more if you are interested. There are some videos on line.