Get a battery replacement on the cheap and power through to the X2. You can even buy it online and replace it yourself if you're handy.
Other than that and than to buy a cheap used phone to power through as well I'd say get an X and move on. You made it to 2018 with a 5s. You won't die with an iPhone X all the way to 2019 or 2020. Or even 2021. The biggest advancements are already there I believe (the display and Face ID). The star of 2018 will be basically the Plus size.
Well, it's not just the battery life. That's my main issue, but it's not the only one. The phone's incredibly frustrating to use.