The higher speed one. 4000 runs at 2.4Ghz and 4400 runs at 2.2. So the 4000 will be faster in straight up single threaded game apps with nothing signifigant running in background.
But many games are coming which will be multithreaded (unreal for example) so I'd say get 4400..plus all the other benefits it provides you like gaming and encoding at same time heavy multitasking effortlessly etc.