If you're looking to fish a reservoir in Mass. then Quabbin is the place to go.
As it's the main water supply for the Boston area, it's a big lake and boy do they have rules
There's 3 boat liveries and you can fish for trout and salmon, but the smallmouth bass fishing is world class
You also may be interested in the "Lakes Region" of New Hampshire. Again, trout, salmon and smallmouth. There's a lot of water to choose from.
Western Maine has many lakes as well.
Quabbin smallmouth from last year