My first ever onsite stay was at the Beach Club and I wished we'd picked the Yacht Club! Whilst it's effectively the same hotel (they're adjoining and share the Stormalong Bay pool), I preferred the decor at the Yacht Club and it has a more adult feel. I don't quite understand the fuss about Stormalong Bay. Great for families, I guess.
We've also stayed at the Grand Floridian. Bear in mind that this is WDW's flagship hotel and significantly more expensive than all the others - presumably for a reason. By the time we got around to staying there, though, it was for convenience more than anything (we spent one night there following a meal at V&A's rather than get a cab back to our villa). At one time a stay at the GF would have been a dream come true, but we've stayed at so many really unbelievable hotels that no WDW hotel could even come close. For that reason I wasn't blown away. I love the hotel itself - Mitzner's Lounge and V&A's in particular - but the room was just a hotel room, IMHO. We were in one of the annexes. Maybe it would have been better if we'd been in the main building.
Would you feel you'd chosen second best if you opted for the Yacht Club? I ask that because that's what I felt when we stayed at the Beach Club. My first choice at the time was the BoardWalk, but it was more expensive (GF was out of the question at the time).
If you really can't decide, toss a coin. Disappointed or pleased? You've got your answer.