Best area for rental property within 40 minutes of Boston?

[Marielle Walter]

I am looking into buying a rental property in the Boston area (it does not need to actually be in Boston) but I want to be able to rent to students and young professionals, as I plan to do a micro-unit, coliving type arrangement, and they will be my target market. I would love to get suggestions on what the best areas could be to look for a house with 3+ bedrooms (ideally much more), in the 500,000 range, that would be a high demand rental market, and of course walking distance to the train.