Westville would be a much better choice if you can afford it, especially considering the commute. It's also a nicer neighborhood IMHO, with more large parks right in the neighborhood itself, plus all the land trusts in Woodbridge, not to mention the Westville Village and its popular farmers markets and festivals.

Many people even walk from Lower Westville to downtown for their commute. It's closer to places like Rudy's than most of East Rock is. It's an easy bike ride from Westville to downtown or about 10 minutes by bus (there are 3 bus lines to choose from, so far better service than what Spring Glen has).

The downside is that the houses might be more expensive these days since that part of the city has been getting even more affluent.

Culturally there are some differences. Westville has a large Jewish population with several synagogues within walking distance, and more racial/ethnic diversity in general. Wealthy Black professionals tend to buy in Westville or Woodbridge for example. Spring Glen does not have that at all, but it has more white Catholics (though Westville also has a large Catholic church). Also Westville is known for having many LGBTQ families.