Samsung Galaxy S5, Google Nexus 6 and iPhone 6 are all set to release this year. All three devices are s tough competition for each other. Though all of them are not suppose to get release at the same time, they are surely getting a back-to-back release.
Samsung Galaxy S5 is already on the verge of release, which is as early as 11th April 2014. It is even available for pre-order at an exorbitant price though. With 16MP camera and 5312×2988 pixels display, it is surely a substantial item. It would have 2GB RAM and internal memory of 16/32 GB, expandable upto 128GB. It will run on Android KitKat v4.4.2 OS.
As far as iPhone 6 is concerned, there is no concrete evidence about its release date, features or specifications. However, speculation is that the device is being launched in September, 2014 and will have bigger screen size of 4.7 inches and 5.5 inches. Thus, the resolution is supposed to be better as well. It can also have a 12MP camera. The storage space is supposed to be the regular 64GB as with the previous iPhone models. It would surely have A7 processor if not a better one as per the rumor mills.
If rumors are anything to go by then, Google Nexus 6 is slated to release in the last week of October 2014. Some of the speculated features that are doing the rounds need special mention. This device is believed to have 2.4 Ghz+ processor, true octa-core. It would atleast have 4GB RAM. It is believed to come in two variants in terms of memory- 64GB and 128GB. The phone is also expected to have 5 inch display with 2k UHD resolution display and 20MP camera.
These are just the conjectures. However, if you were eyeing to buy one of these three, you may have to wait and watch till the official release and feature conformation.