It's an argument for another thread, but if not for BWS, Conan would not have got off the ground and ran for all those other issues.
What does the market tell us? I just checked MCS for prices: the first Buscema Conan in CGC 9.6 is $129. The last BWS #24 is $1225 @ CGC 9.2 while #23 is $450 @ 7.5. Let's leave aside the last two BWS issues as they are influenced by the appearance of Red Sonja, but #19 CGC 9.6 is $359. Most of BWS' issues are classics. Frankly I don't remember much of the rest of the series and eventually stopped buying them at about #60. But yeah, this should be in another thread.