Motorola, a company owned by Google, realised how passionate some people are about upgrades and therefore it just released Android KitKat 4.4 for Motorola Mini, Ultra and Maxx device. It should be coming over the air, mostly in the US and we know for a fact that Motorola has a rather small presence in Europe.
These three phones join the Moto X and Moto G who already have KitKat Android 4.4.
On the other end of the spectrum the HTC One X and HTC One X+, while launched a year and a half ago, will not be getting Android 4.3 or any other subsequent updates. HTC UK went on record confirming this, but the flagship HTC One has a big chance of getting KitKat before the end of the Q1 2014. Of course by the time HTC One gets KitKat, there will be time for a follow up version of HTC One phone, and we will enter the same upgrade cycle all over again.
It is becoming painfully obvious that anyone who wants regular Android OS updates should get Nexus products, or at least a Google Play edition devices.