WHTT vs. Z94 vs. Kiss (as I remember it):
WHTT had tight rotation, heavy reverb, and jinlges. Strong on "pop," mostly the top 20 songs. Never heard anything older than a couple of weeks in a typical day.
WXKS was dance heavy, still had an urban feel, but they cut into WHTT by mixing it up and just going all out, playing heavy rock and hard dance songs back to back, a sort of MTV'sh format. It worked. WMRQ "Q103," did not seem very interesting to me, and seemed like a step backwards with lots of grassy progressive rock songs, low production value, and low energy. Listeners agreed.
Z94 was more Hot AC'sh at first. Not much heavy production value--until WHTT was gone. Then Z94 (and later 'Zou) took over, with very tight rotation, and heavy jingles (but no reverb) beginning yet another battle top 40 battle with WXKS. Z94 was more processed; WXKS had more bass.
WXKS played LP's, and remixed tracks, even older music from the 70s and 60s here and there. Z94 was TIGHT, and only played the short released singles. Everything that Z94 played was also played by Kiss, but not everything on WXKS's playlist made it to Z94's.