Quitting internship at small mutual fund to take part time ER offer at top BB bank?

I'm currently interning at a small mutual fund, with the expectation I would still stay on on for the rest of the school year until summer 2019. I've been doing it for half a year. I don't like it that much here though honestly, and I recently got an offer to do part time ER at a top BB. I'm split on what to do - BB internship has brand name which I am sorely lacking on my resume and will likely pay much better, but I will likely be sort of screwing over my current firm as I was expected to stay on until summer. I will likely not leave on great terms with them, which can be tough to explain if reference checks turn out to be an issue. A lot of AM firms I've been talking to also frankly get hard for buyside experience and they will at least sort of question the move. It's been a big selling point for me so far, but it's also hard to believe that people would rather see tiny mutual fund experience rather than BB ER. They also have my resume and know that I was supposed to stay on until the summer as well.

Any thoughts on this would be greatly appreciated.

Edit: End goal is to end up at a top AM or HF for FT, as well as 2019 summer. SS ER is a distant backup.