David. He was the outcaste, Skye was the only person who bothered to speak to him, other male housemates get evicted and he buddies up with Ryan and ape-man Tom to form some super cool bro alliance. All of a sudden thinks he runs the house, is condescending to everyone around him and is plain crude at times. Newfound friends for him = newfound cockiness
It depends in what context. In terms of thinking she's already won, definitely Skye. In terms of voicing his opinion the longest & loudest, it's Travis. In terms of thinking people like Skye & Travis are beneath him, it's Ryan.
Skye, followed by Priya. Lina is up there too and Leo a little, though he seems a little more worn-out and natural now. I don't think David is arrogant, I think he just gets overly excited when people listen to him and accept him (which can happen to me and people assume its arrogance, but it's just over-excitement).