Sorry I cant just pick one, Soul Class of 66, Up Town Down South, So Soulful 70s, Soulful Kinda Music / For Collectors Only, The Northern Soul Of L.A. Vol 2, simply because it had Troy Dodds and June Jackson on it...
and the daddy of em all for me, Modern Soul Connoisseurs that one Richard Serling put together, cost a about a fiver when it came out, and what a track listing given the normal pit falls of licensing songs from various sources... in fact he mentioned on his show recently that this comp just happened, everything he asked for became available and out it came, sheers quality comp...
Mal.C