Okay, that makes it easy then. Without any hesitation, I recommend "Vendetta" by Peter David, a sequel to TV's "The Best of Both Worlds" (TNG) and "The Doomsday Machine" (TOS). It had a recent sequel featuring VOY's Admiral Janeway and Seven of Nine, but that was met with mixed reviews: "Before Dishonor". If you want more Kirk & Gary ("Where No Man...", TOS) stories, then look for the trilogy "My Brother's Keeper" by Michael Jan Friedman - it's great! For Khan stories, there's a great duology ("The Eugenics Wars: The Rise and Fall of Khan Noonien Singh") and a sequel, "To Reign in Hell") by Greg Cox. As for "City of the Edge..." (TOS), "Crucible: McCoy", by David R George III, tells what happened to the McCoy who saved Edith Keeler's life and was forever trapped in the past. It's a huge novel, but well worth getting lost within for a week or so. The people I stayed with while reading it thought I was being very unsociable.