It should be based on their legend status not necessarily how they compare on playing merit or “best I’ve seen”. For example, as a player Scott Dann probably was better than Colin Harrison, and more of our current fanbase will have seen him play, but Young Colin was a local lad and a loyal servant of the club for 18 years, held our appearance record until Wacka broke it, and played in some of those iconic games that still get talked about from back in the 60s and 70s (such as Man Utd and Arsenal).
Dann is probably most remembered for THAT goal against Rochdale but (or so I’m told - by older fans) Harrison once scored with a free kick from within our own half.
Scotty is off course still playing up there in the EPL (although he never did get the England cap many predicted), but Colin is always assured a good reception when he turns up for former player events (and I recall him playing in some testimonial game featuring a few oldies a little while back - still looked fitter than many who are much younger than him).
So which of the two is more of a legend?