which picture upload option uses more data space?

The space is apples and oranges.  One is file attachment space and they give you a tons of that.  If you look at you plan limits and usage, typically, you will be no where near your limits.  But Application space (ie what you type into the app)  is the "smart space" that allows for all the advanced Quick Base functionality and loads to memory - so that Quick base can be Quick.  So you get much less of that.

So, stick to file attachment uploads.

Perfect response. Thank you!