I would definitely recommend to stay at Ubaldo's place. The house is well located (easily accesible by boat) and the apartment is very clean, has all the necessary equipment and is very cozy is as well! Ubaldo is the perfect host you could ever ask for. He is super kind, always responded real quick and was very much willing to give us some recommendations for where to eat. If you would like to have the best experience in Venice, you want to stay here.