As an English-as-second-language speaker and writer, one thing Grok really shines at is capturing the tone and level of "formality" of a piece of text and the replicating it correctly. It seems to understand the little human subtleties of language in a way the other major providers don't. Chatgpt goes overly stiff and formal sounding, or ends up in a weird "aye guvnor" type informal language (Claude is sometimes better but not always).

Grok seems in general better at being "human" in ways that are hard to define: for eg. if I ask it "does this message roughly convey things correctly, to the level it can given this length", it will likely answer like a human would (either a yes or a change suggestion that sticks to the tone and length), while Chatgpt would write a dissertation on the message that still doesn't clear anything up.

Recently I've noticed that Grok seems to have gotten really good at dictation too (that feature where you click the mic to ask it something). Chatgpt has like 90-95% accuracy with my accent, the speech input on Android's Gboard something like 75%, Grok surprisingly gets something like 98% of my words correct.