Finance - Tax division for Sophomore Internship vs investment banking internship at a small regional bank?

I am currently a sophomore and I was offered a position in the Finance- Tax department at a major bank.
First of all, would you consider this back office or middle office?
Secondly, do you think that this is a good precursor to an IBD internship in my junior year?
Would it be better to do an investment banking internship at a small regional bank?

Thank you very much!