If the budget allows, I’d recommend staying somewhere in MK area. When my kids were 2.5 and 4.5, we stayed at the Poly and it was worth the money to me for the convenience. Using the monorail meant not having to fold a double stroller or wake up a sleeping child, so it was very convenient for getting up early and coming back midday for naps while not having to worry about wasted time waiting for buses. We loved Ohana, Trader Sam’s and Pineapple Lanai. The volcano pool has zero entry beach and a splash zone, but we actually preferred the quiet pool since no one was there (and my kids didn’t enjoy being splashed at that age).
Like others have said, I wouldn’t worry about theming choices in regards to toddler appeal- at that age they are excited about anything and just spending time with you- so pick whatever would be the adults’ preferences, based on convenience, pricing, dining or bar options, or combo of these.
Case in point: The thing my two year old son got MOST excited for the whole trip....ducks in the grass at MK. Not Donald and Daisy Duck, but real wildlife that were resting, he wanted to watch them for like 30 minutes. And he LOVED the tiki torches all over Poly property that are lit at night.