Best "Starter" Lens Upgrade Under $500? (Not a kit lens fan)

Hey everyone, I'm Sarah Chen, a cinematographer, and I'm currently prepping for a passion project that's going to be shot on an FX6. It's a drama, and I'm really trying to elevate the look beyond what a standard kit lens offers, as so many guides emphasize the importance of good glass. I've mostly worked with higher-end rentals like my usual ALEXA Mini LF setups, so my personal lens kit is pretty... bare. I’m wondering, what’s a specific prime or zoom lens, priced under $500, that you’ve found provides a significantly better image quality and performance than a typical kit lens? I’m looking for something that offers a really noticeable jump in value for that price point. Any recommendations?