I can't comment on the Wyndham. I did stay roughly 15 nights each in the Hilton LBV and DoubleTree Suites during 2014.
Hilton Lake Buena Vista: An average hotel with a fantastic location. The ability to walk to Downtown Disney is the main feature. The rooms are quite generic and the food & beverage outlets are expensive. Although I hate generalizations, I'd categorize the employees as "disinterested". Sometimes getting little things accomplished (like having a missing iron delivered to a room or getting a running toilet fixed) takes an hour or multiple phone calls. I only recommend this place if you are a Hilton HHonors Gold/Diamond member (which means you get continental breakfast) or if the room rate including the $24 resort fee is under $100.
DoubleTree Suites: I love this hotel. As HopperFan notes, the renovation on the rooms was well done. The only minor annoyance is the lack of a fan in the bathroom. Although a longer walk to Downtown Disney, you can easily walk over to the Crossroads Shopping area for cheaper food options. The DoubleTree employees are the exact opposite of the Hilton. I've never not gotten a "Good Morning/Afternoon" when walking past a Housekeeping employee in the halls. Getting small things like extra towels get handled quickly. I've even gotten several thank you notes from Housekeeping for leaving a tip. The fact that I have received consistently good service across multiple stays says a lot.