I had a Mizuno TP Mills forged putter years ago that was sweet. Probably should have refinished it. Definitely one of the best feeling putters I ever used, but it only worked well for maybe half a season lol.
I did try some of the more recent Mizuno putters which I think are forged and then milled and they were really nice, but I didn't get the "feels". I've had other putters that were carbon steel, but I don't think they were forged, but just milled/machined. Unfortunately that is the extent of my forged putter experience.