It's hard not to like the Xiaomi Redmi 4 Prime. Superb metal build, premium looks, exceptional battery life, good display and camera (if neither is exactly trend-setting) - all of this for what amounts to $130 in China. That right there is the operative word, though, China, as the phone is still not available outside of its home country.
Going through the list below you won't find major dealbreakers, even if some areas could use an improvement. Sure, audio quality when recording video isn't great, and camera output won't please the most demanding users but do we seriously expect a phone in this price bracket to be perfect?
It's hard to beat the Redmi 4 Prime's solid package, particularly at its price point. What's probably going to be an issue is actually getting your hands on one outside of China. Importing it would drive its price higher. Not to mention that so far the ROM is heavily geared towards its home market, and unless an international version gets released, you'd need to settle for some UI elements in Chinese even when you switch to English.
Most of this applies to the Redmi 4 non-Prime as well. Availability is sketchy, but it's even cheaper while looking exactly the same. The display isn't as sharp at 720p, RAM is 2GB vs. the Prime's 3GB, storage is half at 16GB, and the chipset isn't as great. It's a steal at $100 in China, or about $130 imported.
The older generation Redmis are more widely available and slightly cheaper than the Redmi 4 Prime too. Some of them also have international versions already out. The Redmi 3S Prime, for example, matches the 4 Prime in most areas (RAM, storage), though the Redmi 4 Prime is the only one so far with a 1080p display and the efficient Snapdragon 625.
If you do insist on an affordable FullHD 5-incher, Lenovo might have a few models to offer. The Vibe K5 Plus quickly springs to mind, though it fails to match the Redmi 4 Prime in RAM, storage, battery, or processing power. But it is widely available, and runs on international software, albeit an older Android 5.1 Lollipop. The Lenovo K6 addresses a few of these concerns, bringing Marshmallow and a 32GB storage option, plus an 8MP selfie camera. It's pricier, though.
Meizu announced the m5 recently and it matches the Redmi 4 Prime's price. It's got a marginally larger display, but its resolution is lower at 720p. The Mediatek chipset inside is unlikely to be as efficient as the S625 and combined with a much smaller 3,070mAh battery, the m5 can't compete with the Redmi for endurance. The same availability caveats apply.
The Sony Xperia E5 is an entry-level 5-incher from a premium brand, and what that means is a 720p display too and half the storage and RAM of the Redmi 4 Prime, for a higher price.
Overall, if you're in China, the Redmi 4 Prime is a no-brainer. If you're somewhere else in the world the math gets trickier, but the phone itself doesn't get any worse. And it's such a great deal to begin with that even importing one over gray channels still puts it high on the value for money meter.
Special thanks to HonorBuy for providing the review unit.