Sorry it's been so long to have replied to this post. With covid and other family issues, I have not been out fishing much in 2020. However, being an old "codger" I've fished my way through the Berkshires and most of western MA all my life.
If you are looking for "big" (of any species), I'd highly recommend the Quabbing Reservoir, hands down. The Oxbow in Northampton has produced some big bass and pike over the last several decades; as long as you're willing to contend with heavy warm season boat traffic.
Other great lakes are Onota in Pittsfield and Pontussuc just north of there. There are other smaller bodies of water in and about the Brookfield areas that produce as well. Like any area, when it comes to fishing, you just have to put in your time on the water. And having a good sonar is a big plus as well. Good luck to you and let me know if I can be of further assistances.