Your local Penn State U has recommendations for fall/winter cover crops, and I'd recommend you check that out first.
Learn about cover crop species and varieties, seed choices, and usage. Use Penn State Extension resources for successful cover crop management.
extension.psu.edu
There is no such thing as the "best" cover crop as it depends on what properties you are looking for and where you are located. The referenced article lists 4 fall/winter types as follows winter canola, cereal rye, red clover, and hairy vetch. I have grown each of these in my location. They are all excellent.
I especially like Elbon rye for winter cover as it is great at weed suppression but also deters root knot nematodes which may or may not be a concern of yours. Red clover is one of my favorite covers for its nitrogen fixing properties and staying power in winter. I don't use much canola, but I do understand it is an excellent choice for your area. Hairy vetch is always in my portfolio but only in combination with others such as red clovers and/or rye. I'd recommend you consider not just one but a combination of more than one of these.
My favorite fall/winter cover is alfalfa as it has powerful nitrogen fixing/soil building properties...but it may not be practical for your area. I just don't know. I also use a lot of root crops like turnips, dakron radish, also brassicas but don't know how they would do in your winters.
I'd encourage you to "do your homework" and that article is a good place to start for your area.