Userguide videos (Interactive, if possible).
However, there are some things which are always best suited as a list. I have never been able to rule out one of these.
So for me, it goes hand in hand with a little bias for videos (I am more inclined towards videos and only essential docs/ checklists).
Depends on the product - sometimes it helps to have detailed documentation if I want to refer to it at my own pace, especially if there are several steps involved.
Videos are useful if it's a quick tour that doesn't require my involvement in every step.
Ultimately, combining both approaches allows you to take advantage of their respective strengths and learning styles. Reading documentation provides detailed information and quick reference while watching user guide videos offers visual demonstrations and practical examples. This hybrid learning approach can enhance your overall understanding and proficiency with the SaaS product.