Well, of course, you have to take out any negative connotation and leave only positive options. Fortunately, there are very well-known (and tested) examples: the original Facebook (only one Like), Netflix, YouTube, and so on.
Facebook introduced reactions to express something other than just "Like" after much discussion about adding a "Don't Like" button. Since these features have been tested for years with billions of users, I think it's a good idea to take inspiration from them.
With the current FB reactions (and one that will supposedly be added in the future, though I doubt it), you could do something like this:
These are all positive, although I don't think they have a well-defined sort of gradation.
So I created a version based on the images above:
Of course this is just an example, but I think it has a more defined grading that can be translated into a 1-5 scale.
The Likert option
Another idea would be to take inspiration from the Likert scale and apply it in a playful way. For example, you could use a scale like this:
How would you rate [x]?
Good - Very good - Excellent - Outstanding - Out of this world
Using the same idea, you could use variations with definitions from sports or comedy or whatever.
Of course, your target audience needs to understand the reference. For example, if you say, "That's a home run," I understand the reference because of movies. However, if you say something else about baseball, I've no idea what you're talking about.
The same goes for your audience: your language must be understandable to everyone, without limitations.