I have used Florida Master and they were cheaper than Thomas Cook! I got the Animal Kingdom hotel for the same price as Coronado Resort!
We've booked the entire package through Disney for our trip this year. They are now part of Disney and based in the USA. This has been the case for around 12 months. This is so that all uk bookings can be part of the my magic plus system I was told.
Our last trip was booked through Disney also but this turned out to be a subsidiary of virgin Atlantic acting on behalf of Disney. We had a few problems with the dining plan but other than that it was fine.
The reason we booked through Disney was as we booked ago far in advance we wasn't able to book any flights, Disney offered us the chance of reserving these meaning I don't have to worry. As it turned out we have paid an extra £5 per person per flight compared to virgins recent prices, so for the peace of mind I think it was worth it.
We've used them the last 4 or 5 times and (so far) have never had a problem. We got $200 for each booking to spend in 2012 and again for this year (and I made 3 bookings all together) so that was a bonus. They've always been incredibly helpful but then I've only ever spoken to the WDW USA for bookings etc 'cos it's a toll free number