Hi there!
I was recently accepted into both programs as well and have thought hard about this too. Columbia has always been my top school and to find out I was accepted was a literal dream come true. However, after talking to my POI, who in essence guaranteed there wouldn't be any internal funding for free-standing MA students, I am strongly leaning towards turning it down. $100K just for tuition is honestly unreasonable for me, especially for a MA. The BGC on the other hand has offered me a generous scholarship (though not full funding) and has been extremely eager to help in answering questions about the program which definitely alludes to the close-knit, inclusive culture they promote. And like you said, they have the required study abroad and abundant internship opportunities abroad, which is obviously really appealing. I am still waiting to hear from the Courtauld, another top school for me, but right now I am definitely leaning towards the BGC. Let me know if you're planning to go to the accepted students day!