I have always been a .com fan, with .net a slight second. .com domains will always be the powerhouse tld. Though with the opening of the .com.au market, and living in Australia, it has never been a better time to target aussies, and pickup aussie domains for development for a percentage of the price of the .com counterpart. Im actually a huge fan of the whole domaining industry and wherever theres money to be made, i know ill try and make the most of it. In terms of other domains such as .tv, it is nearly all speculation on whether these domains will be popular or not, but for a small amount of money to risk, its nearly worth buying up a few domains to keep just in case.