It can be picked up for a similar price to the S4 - a little under £300 on Amazon - but for our money the HTC One is the better all-round phone. Performance is similar, but I prefer the One's UI tweaks and its general feel.
Unlike the S4 it feels every inch the premium phone, with an all-in one aluminium chassis that's only been matched (on Android) by its successors.
Having said that, the S4 has a better camera and is lighter in the pocket, which means it'll be the better bet for some.
- Read our in depth HTC One review
Google Nexus 5
Google's ageing flagship remains one of the best-value smartphones out there, though Google has just stopped selling it direct.
The Nexus 5 may have a marginally inferior 5-inch 1080p IPS LCD display (though some may beg to differ) but it outstrips the Galaxy S4 on performance with a superior Snapdragon 800 CPU.
The Nexus 5's 8-megapixel camera is inferior to the Galaxy S4's 13-megapixel example, but it is competitive on price at £250-300, and the recent upgrade to Android 5.0 is a massive plus.
- Read our in depth Nexus 5 review
We're a little conflicted about putting the OnePlus One on here as a viable alternative. It's better than the Samsung Galaxy S4 in virtually every way, barring possibly its camera and lack of expandable storage, and a case could be made for the Galaxy S4's Super AMOLED screen technology (though the OnePlus display is half an inch bigger).
Meanwhile the OnePlus One's Snapdragon 801 CPU, backed by 3GB of RAM, makes it a performance match for the Samsung Galaxy S5, let alone the Galaxy S4. It also runs an OS that's even more flexible than TouchWiz, but with a better stock Android style.
And all that for just £230 brand new for the 8GB version, and £270 for the 64GB model. The trouble is it's still very difficult to acquire one, thanks to limited production numbers and a torturous invite system.
- Read our in depth OnePlus One review