You Want Storage Options
If you want RAM and storage options, buy the OnePlus 6T. In a market where most phones come with 64GB of storage and only 4GB of RAM, maybe 6GB, OnePlus gives you choices.
You can get the OnePlus 6T with 6GB of RAM and 128GB for a low price.
Or, you can choose a little more RAM for better performance and pay just a few more dollars, getting the 8GB model with 128GB. And finally, they have a third 8GB RAM and 256GB storage model that's still only $629. Making it far cheaper than something like the 4GB RAM and 64GB storage $900 Pixel 3 XL.
Crazy. If you want options, buy the OP6T. Just remember, there's no microSD slot. Get the Galaxy S9 or Note 9 if you need expandable storage.