Summer Internship at BB or boutique?

Hello community. This one probably was asked before.

I’m from Portugal, which don’t have a huge reputation on placing graduates in IB, also my school is on top 3 (university of Lisbon) but only 2 (Nova and Católica) are famous outside Portugal. I’m a full time worker, since I’m 16 and I’ve never stop doing so while studying. My GPA is not bad, it’s 14 out of 20 (Portuguese grade system). By doing this, what strategy you think would yield me the best result in landing a summer internship in a major financial hub, should I focus more on smaller banks/boutique than BB, or should I consider other alternative scenarios?

Thank you in advance!