I have stayed at Hilton and Novotel before. My opinion is Novotel is far better than Hilton. It's kids club is good, the hotel is very spacious. However, it is far away from Hua Hin downtown. Last time I went to Hua Hin is by self driving, so distance is not a problem for me.
Hilton is near the downtown, the night market is within walking distance.On the other hand, Novotel is near the Santorini theme park and water park, Swiss Sheep Farm than Hilton, so depends on where you go.
You can check their location in Google map.
I have not stayed at Sheraton before but many jm here recommend this one.
BTW, I have went to HuaHin vineyard and have a delicious lunch there, however, it's a bit far from Hua Hin downtown, just for your reference.