I used to work in Providence quite a bit...I've done most permutations of travel to/from there using BOS, PVD, various connecting airports, rental cars, Ubers, different train options, that Silver bus that is almost as good as a train, and occasionally water taxi.

At the end of the day, I flew out of BOS probably 75% of the time. Always *wanted* to fly out of PVD because it's such a small, pleasant, easy airport, but the connections rarely were efficient to get back to MCI. Never an IND or STL or even a MDW. It was usually BWI.