cd and Necrat both make excellent points here.
As someone who analyzes FM signals for a living sometimes, there are a lot of factors I take into consideration, and this thread has touched on several of them.
There's total coverage - what signal covers the largest area, period. WHPT wins that crown in Florida, being a 100 kW facility from the tallest FM tower around. But there's also total land area coverage, where WHPT (and any of the coastal stations) fall flat by virtue of how much of their signals are expended over water. And there's total population coverage, where again WHPT falls a little short because it's in such a rural area so far from the big population centers.
Then there's the question not just of signal coverage, but of penetration. That's less of a critical factor in a state like Florida, where the buildings are low-slung, but it can be a very big deal in a denser urban market like Boston or New York or Chicago. Just because a signal appears on paper to have 60 or even 70 dBu coverage of the urban core doesn't always mean it can be clearly heard there if it's coming from a more distant site outside that urban core. Even a few miles can make a big difference in a situation like that. In Florida, this plays out as the difference between a Riverview FM and a Holiday FM (97.1/97.9/105.5) in an area like downtown Tampa or southern Hillsborough County, or as the difference between the Bithlo FMs and the Orange City FMs (101.9/105.9/107.7) or WCFB in Kissimmee.
In a state like Florida with big signals and fairly closely-packed markets, just having a huge signal isn't always enough. WCFB, again, is a good example: sure, it's a beast of a class C signal from a tall tower, but it's so far north that much of that signal is effectively wasted outside the market. Sure, it's nice to be able to hear WCFB in Ocala or Palatka...but Cox doesn't sell ads in those places, and those advertisers aren't going to pay Orlando rates to reach whatever listeners might be tuning in there. If Cox were able to trade the huge WCFB signal for a slightly lesser signal better-centered over the market, it would surely do so in a heartbeat. Same thing for WPCV...yeah, you can hear it in both Tampa and Orlando, but that doesn't mean it can charge ad rates that match that reach.
And then there's the increasing real-world limitation of co- and adjacent-channel interference. As the FM dial gets ever more crowded, it's rare to find a big signal that's limited only by how far its own signal goes before petering out. Again, WHPT is a good example...it's still putting RF over parts of the Orlando market, but it's now blocked out of listenability by the 102.5 Orlando translator.
There's also this thing called "terrain," but that's not a factor in central Florida...
In practice, the good signal analysts will tell you that for any given market, there's often one "good site" from which several stations provide essentially equal coverage. For Orlando, that's Bithlo, and it's pretty hard to draw any meaningful distinction among the big FMs there - 92.3, 96.5, 105.1 are all pretty close to ideal for dense signal coverage of the entire Orlando market. The Orange City Cs (101.9, 105.9, 107.7) all come close, and what 106.7 (and even 95.3 and 98.9) lose in wide-area coverage of the market's fringes, they make up for with their more central location at the core of the market.
Same deal for Tampa - you want to be in Riverview if you can, and the FMs there are all on a very level playing field. 93.3, 101.5, 100.7, 103.5...they're all very close to identical, and all very close to perfect when it comes to full-market coverage.
