Whichever fits you best. For me that would be the Fox Sterlingworth. Although on the heavy side, I would not rule it out, assuming it is appropriately choked for whatever type of bird hunting you intend to do. Light it is not, but for bird hunting it still carries well and you are unlikely to check your swing with it. And it would keep you in the same gauge as you are currently in, if that matters to you.
Second choice would be the 20 gauge Model 37.
