I went for the XS Max 512 GB option and have about 130 GB free at the moment.
Tomorrow I´m off for a four week trip across Australia and New Zealand and I´ll be using the iPhone as my main camera for videos and pictures as my DSLR broke a little while back and I haven´t bought a new one. With 4K video the storage space will be truly appreciated as I don´t know how often I´ll be able to have fast Wifi to do online backups of the pics and vids and unload them from the phone.
And with 512 GB I´m able to have lots of offline music and videos for when stuck at the airports, long flights etc. I have an iPad Pro 11 256 GB for the longer streches of content consuming but the iPhone is just so much more available for catching a quick episode of a TV-show or enjoying some great music and podcasts stored offline. I´m also able to store larger offline maps for navigating.
In my home country Norway we don´t have unlimited data plans for mobile, most people have data plans with around 1-6 GB, and some upto 20-40 GB, data per month which isn´t that much when you stream high definition video, good quality music, use the phone as a hotspot to other devices and so on. So having extra storage is much appreciated when you are on the go a lot as I am myself so the data plan can go to better use when hotspotting to my laptop on the road etc.