This is the most basic level of eval, of whether they can produce output that will be considered by someone somewhere (usually a young urban US American) as informal toned. Real human communication is far more nuanced than this, different groups have different linguistic registers they're used to and things outside it sound odd even if they can't articulate why. You could also want to be informal but not over-familiar with the other person (for eg. in a discord chat to a new acquaintance) - actually looking at the outputs here, the Claude output seems best fitting for that (in my subjective view anyway) than to the one you gave it - or want many other little variations.

What makes one cringe and another recognize as familiar and comfortable is also pretty subtle and hard to define. These things need nuanced descriptions and examples to actually get right, and it's in understanding those nuances and figuring out the register of the examples that Grok outshines the others.

you said that English is not your first language, so heads up - you don't need "for" when you use "e.g.", it already means "for example".