Was using Reveal.js which worked well because it can use any HTML or any plugin.
Bento works with a predefined schema, so you cant use any HTML library (Such as Mermaid.js) if you need it in your presentation.
But then again, often you dont need it.
Just created a presentation with Bento... I do think Reveal.js gives you more raw power. But I like bentos single html page design, and you can easily edit it manually. You cant do that with Reveal.js