A good rule of thumb when choosing a winter stream is to focus on the streams that stay the coldest in high summer in the same general altitude range. These creeks will have the strongest spring inputs and thus will have the most open water and highest winter water temps.
While this is sort of a DUH as to why winter spring creek fishing (as in limestone influence) is worthwhile, there are also a lot of PA freestone watersheds with strong ground water input that puts them head and shoulders above other freestone streams as winter choices.
Just for a few examples in Western PA, the Sugar Creek watershed in Crawford and Venango County, the tribs of Oil Creek above Titusville, the open sections of the Spring Creek watershed in western Warren County. Although I don't know for certain, I'd assume that stream that run out of the moraine sections of the upper Allegheny drainage in McKean and Potter counties would be similar.
Another tactic that works to an extent for finding good winter streams is to find ones where small municipalities have built small waste water treatment plants. During the PennVest push of the 90's, a lot of small towns ended up building these facilities and there are a fair number of them on ANF streams, for example. Depending upon their flow/volumes and how good of a trout stream they discharge to, these can also provide better winter destinations due to water temps.
On most of these creeks, we aren't talking about January water temps in the 40's, but you might find a fair number of stream sections that routinely run in the upper 30's. And that's fishable water if you have the patience to fish low and slow.
Just a couple thoughts...