The Nexus 5 and Samsung Galaxy S5 represent two approaches to making a flagship Android phone. The Nexus is designed with a few hardware compromises, but makes up for that with an amazing price and great software. Meanwhile, Samsung's device has all the bells and whistles (sometimes ones you don't even need) with more heavily customised software and a higher price. There's no doubt both these phones should be on your shortlist if you're looking to upgrade right now, but you've seen the specs, so let's check out how the experiences compare.
Samsung has cleaned up its act with regard to the speed of its Android ROMs. As recently as the Galaxy S4, TouchWiz caused strange slowdowns, even with cutting edge hardware. The Galaxy S5 seems every bit as responsive as stock Android in daily use. Swiping through the home screens and launching apps will no longer make you want to pull your hair out. Google's stock build of Android is generally a bit more elegant and thoughtful – it's still preferable, but not by as much anymore.
You're probably not going to restart your phone on a daily basis, but it's surprising how much speedier the Galaxy S5 is to start up compared to the Nexus 5. I have the Galaxy S5 clocked at a hair over 20 seconds to come alive from a cold boot, which is darn impressive. The Nexus 5 takes about twice as long to hit the home screen. The Galaxy S5 is even usable as the system finishes loading all its background tasks and services (which are still more extensive than the Nexus). The Nexus 5 takes a little longer to get everything sorted out and become smooth.
That's not to say the Nexus 5 is a slouch, and once it gets fully up and running Google's flagship can launch apps and load web pages roughly as fast as the Galaxy S5, even though its processor is a bit older. It seems like the Galaxy S5 might beat it by a blink on average, but it's close enough that you shouldn't worry too much about the general performance.
The fact that the performance and smoothness of operation is almost the same is a big win for Samsung. Not only has it made TouchWiz look nicer, it doesn't get in your way to nearly the same degree it once did. Aesthetics will vary, of course, but Samsung's new UI is more neutral and less grating than it once was. It might not be as clean as stock Android on the Nexus 5, but it's a big step in the right direction.
Samsung also has all those unnecessary face-tracking and gesture services disabled by default, which probably helps it keep up with the Nexus. You can turn all that stuff on if you want, but it's tucked away safely in the settings where it need not otherwise bother you. Even the camera has been spruced up with a cleaner interface and fewer preinstalled effects. Again, you can add more features if you want (via the Samsung app store), but it's faster and cleaner in the default configuration.
There are still two more abstract concepts you should consider that don't come across on video. The Galaxy S5 costs £579 off-contract, and the Nexus 5 is only £299 in comparison – though you can of course get an S5 on contract deals to avoid a big initial outlay. Depending on your situation, one or the other option might make more sense.
Then there's also the question of updates. Samsung's build of Android 4.4.2 is good, but Android updates are unstoppable. When Google announces the next version of the platform – possibly this summer – the Nexus 5 will get it right away. Samsung Galaxy S5 owners will be left waiting at least a few months.