In all sincerity what makes BLT special, in your post above you stated it was the ability to watch fireworks from your balcony (if you book theme park view and some lake/standard)--something Riviera does provide with similar views (parking lot, trees, park). My gripe with Riviera is they should have added a third view classification of Theme Park View just like BLT to guarantee those firework views. Personally, BLT to me is just convenience it offers nothing more (over any of the other MK resorts) than convenience, and that is if you want to spend most of your time at MK (with occasional time at Epcot). Decor style BLT is very generic in the sense it is "modern" of a certain period in time and in the short future it loses the "most convenient" MK resort title to a tie likely. I've always been curious on BLT as I want to try it but feels similar to me as Riviera feels to you, I guess.
To me AKV is entirely different and THE most unique of all WDW resorts (hands down, though I really don't like the dark rooms) so I definitely get the sentiment on that one.