For me it has to be this.......
I love the modern sleek facade and the tapering shape of the design..for me one of the top skyscrapers today
I also like the trump tower in chicago... It also has a sleek facade but also pays homage to the older chicago skyscrapers in its bulky design and step backs
How about bahrain world trade centre...not the best looking but i like the way the architect used sail like towers to direct the wind to the wind turbines...plus making it suit the location (seaside)