If you know XNA, then you may want to consider using MonoGame, an OpenSource implementation of XNA that works on iOS, Android, MacOS, Linux, PlayStation Mobile and Windows 8.
MonoGame powered games have been released on iOS, Android, MacOS, Linux and Windows 8 Store. There are already over 20 MonoGame powered game on the Windows 8 store alone.
Examples of high profiles games that have used are award winning Bastion, used a fork of MonoGame on iOS, MacOS and Linux. Draw a stickman : Epic released on iOS, Windows 8 and Android and has been top 10 on each of those stores/market places. Wizorb has been been released on MacOS, Linux. There are lots more example available from monogame.net.
ARMED! has been the poster child of Windows 8 games and can be seen a quite a few Microsoft adverts for Windows 8.
Basically all types of games are using MonoGame and been released on various stores.
In the future we plan to support PlayStation Mobile, Raspberry Pi, we already have initial Windows Phone 8 support.
Try it out and make up your own mind.