Unless one is forced to, one should never consider direct financial compensation when deciding whether to accept one particular internship versus another (regardless of the field of endeavor). The decision should always be based on other grounds, ignoring the immediate compensation. I offer this very good advice knowing that it will be ignored by nearly everyone, possibly even everyone.
So long as the work is in your field you need to find the opportunity that values what you do and is able to leverage it. Demonstrating that you found someone that can't find value in your work can work against you.
I never suggested that it should be the only metric. But for graduate students, especially those with work experience, it is pure abuse to let them toil 8-12 hours a day for 3 months straight and throwing some pittance at then. If the employer already treats interns like that then how do they treat their customers or full time staff? Or what does this say about the learning experience for interns?
Early in a career there are things far more important than compensation; yet I know that most everyone will be swayed by compensation rather than the considerations they should be giving the most weight to... as a matter of fact, compensation may be in some instances inversely related to the value of an internship.