VFR Day or VFR Night?
I'm not answering the question because it's contrived and lacking detail and doesn't match anything all that likely in the real-world.
Airplane isn't falling out of the sky. Electrics off, VFR Day is not even that urgent, let alone an emergency. But, fires on aircraft tend to be very bad things.
Landing at the nearest suitable airport means either you've decided you can make the bingo airport with a power setting change to make it "less close to bingo", or you're headed for the airport in the Bravo and exercising your emergency authority.
Night adds some other problems and I'd treat it as an emergency knowing in my mind, that nothing's really different from Day VFR, but there's a lot less options for landing out below, and more than one person has been surprised when they realize that they can't turn on the pilot-controlled runway lights at a whole lot of airports without a radio/electrical system.
And of course, someone else already brought up possible changes in the scenario like having a hand-held radio on board.
This 150 mile fictional airport that's further away than anyone ever sees, even out here in the "unpopulated" West (okay, I can't speak for Alaska or Hawaii...) so given the scenario at face value, I'd choose the Bravo. Arrive overhead above TPA and circle and wait for a light gun. No light gun or first sign of continued on-board fire, I'm landing.
Hell, with the options of airports given, there's probably ten or twenty places in nearby fields/roads that are completely suitable landing locations if it's Day VFR in a typical spam-can, but that'd be an option quite a way down on the list in an aircraft that's flying just fine.
Electrical problems do have a way of being insidious, though. Whatever caused that short also caused something to heat up pretty good, most likely. If that was all happening in a very bad place in the aircraft, you probably don't want to spend a solid hour plus a bit, droning along (at the speeds my airplane flies at) unless you're comfortable putting the aircraft down in the terrain below and handy with the on-board fire extinguisher.
What? You don't have a fire extinguisher? You're nuts.
You could experiment with things like Battery only, vs. Alternator, but you're just asking for an in-flight fire doing that. Better have a landing spot picked out right below you if you're going to try that one. That crew that had that sizzling RADAR that wasn't properly labeled INOP and disconnected, tried to play that game and died trying.