So I am sitting here on a live Arch linux (EndeavorOS) desktop using GParted to move my RaspiBlitz data drive from a 500G SSD to a 1T SSD. I find myself wishing I had sprung for the 2T SSD because sitting here waiting for the damn data to copy over, while still not knowing if this is going to even work, and knowing I will just have to do it again in a few years? Well... let's just say hooray small blocks.
The blockchain grows about 50G per year, so you're good for another 10 years. 1T sounds like the right choice.