For vintage, my 1982 Jack Taylor with Reynolds 531 db tubeset is the best climber. Interestingly my 1971 Mercian with Reynolds 531 db tubeset is not a great climber. Both bikes share the same style 531 transfers, but the Mercian's bare frame is about 1/2 lb heavier, so I suspect the Mercian may have a thicker-walled tubeset than the JT. Reynolds 531 came in a variety of gauges and butt profiles, so who knows what the builders of those bikes actually used. My two modern steel bikes are the best climbers of all. My Rawland is made with Taiwanese thin-walled tubing of known thickness (.8/.5/.8) but unknown brand, and my Jeff Lyon is made with a mix of tubing brands, also thin-walled (.7/.4/.7 and .8/.5/.8). The two bikes climb about the same. I find the practical difference between a good climber and a bad climber manifests as the ability of the good climber to repeatedly tackle the same hills with a higher gear than the poor climber.