I absolutely love the discworld series!! I haven't read all of them so I couldn't say which of those is the best, but moving pictures wasn't bad. I'm really more partial to the city watch "series" that starts with Guards Guards! I will say that I didn't really get sucked into the "death" series that Reaper Man is a part of.
Here's a site that shows the various orders you could read them in:
https://www.discworldemporium.com/reading-order/
They have overarching storylines that connect books, but I don't think you need to see them as Book I, Book II, Book III.
The titles are: