I've been pretty agnostic when it comes to quartz vs. mechanical. That said, I have come to appreciate the fact that unless something goes very wrong, a decent mechanical watch won't just stop all of a sudden, unlike quartz watches in my experience tend to do. (I've had batteries die prematurely, a solar powered watch that "keeps working up to 6 months in total darkness" stopped within a month or two after long shirt sleeve weather started, etc.) The fact that the watch keeps ticking is a bigger priority to me than absolute accuracy. A watch that shows me it died at 10:34 does me no good, whereas if I know my watch is 6.5s fast per 24h, and I know how and when I last set it, I can figure out the correct time to the second if I really need to. Which, thus far, I haven't needed to. It's more important for me to keep track of the time in a more general sense - whether I'm a minute off is less important than knowing the approximate time.
Plus, in my personal opinion that F-91W would look real dorky on a grown man's wrist. Life's too short for an ugly watch...