This is our very first trip to WDW so we have no experience with any of the options, which makes it really hard.
Polynesian looks like a really nice option and pros, it has the monorail available (which our son would probably be super thrilled with), being able to watch Wishes and the Electric Water Parade from the beach, nice tropical/vacation feel, decent quick service food option for breakfast. Downsides are the volcano slide is going to be way too scary for our son (who's almost 9, but very timid) based on a video that I watched. He doesn't like anything enclosed all the way and really dark like the volcano one is and other con, being there's no hot tub (which is also one of our favorite parts of any swimming excursion). Also, I'm a bit leery of the theming feeling too "tacky" mostly based on a local Polynesian option we've done in Wisconsin Dells which was built around the same time as the WDW Poly, but has not aged well and feels so tacky to me. I know the real WDW option would likely not feel like that from photos and video I've watched though.
Wilderness is probably out because we have Great Wolf Lodge that we frequently visit in Wisconsin Dells a few hours from us and the theming feels a bit too similar, so it's not as exciting to us (although the lobby is beautiful).
GF looks beautiful, but is a little too "fancy" for our tastes especially with a young boy. Seems more like an adult type of theming.
Beach Club/Yacht Club also look very nice and we like the option to walk or boat to Epcot and Hollywood Studios. But not sure how much time we'll really have for swimming or what the weather will be like in early/mid March either. Plus again, it's a fancy waterpark which we have lots of at Wisconsin Dells and the slide looks too scary for our son at this one too.
So that would leave:
The Polynesian
AKL looks really cool (and I like the feel from pictures better personally than the Poly), but we probably would not get the upgrade to a Savannah room, instead would have a standard view (parking lot, buildings, etc). We booked garden view royal room at POR as it was the only one available at the time. Other downside being that it's more out of the way, especially since we only plan to do one day at AKL and our room wouldn't have a nice view unless we get super lucky at check-in.
Boardwalk Inn - The pool area at this one looks really fun and like something our son would enjoy (the crazy clown slide, animals around the pool, etc). Downsides are really not much for quick service options for breakfasts/fast meals and a bit more adult feel to the resort from the pictures we've seen.
So that's where I'm at now, but again, it changes hourly (ok, every few minutes). I've decided several times on Poly first because it seems sensible and like something everyone keeps recommending and there are some really nice options. Then maybe AKL next because it's interesting to me. But then I throw some of the others back into the mix and go nuts