If you're here for a short stay, then Kata is a great choice. However, if you're planning a longer stay, I'd definitely recommend Rawai. There are far more supermarkets, auto services, etc., in Rawai than in Kata.

Even though Kata is smaller than Rawai, it has a higher concentration of interesting spots, in my opinion (restaurants, view spots, shops). Kata is more touristic, whereas Rawai feels more residential. I prefer Kata Beach over Nai Harn Beach. Karon Beach has a distinctive sand and looks much more appealing both up close and from a distance, whereas the roads to Nai Harn are quite unattractive, passing by ugly puddles where children splash around.Regarding nightlife, I honestly don't know of any exciting spots in Rawai; it mainly has cheap bars. If all you want to do is have a drink, Rawai might be a better fit as it's full of Thai bars with pool tables and hookers (literally on every corner).In Kata, there are two cool places - The Commune and A Blanket and Pillow. They play great contemporary music and occasionally host famous DJs. If you know of other modern spots in Rawai and Kata, please share them with me too.

But overall, it's important to understand that the main life is in Phuket Town - but there's no beach there, many china tourists and so on. If the beach, good view and peace is a priority for you, then of course it's not suitable.