Lightning cables
The cable that you use to charge your iPhone is called a Lightning cable. There are various versions of these. Of course there is the cable that Apple makes. Then there are cables that Apple certifies, which means that they are guaranteed to work with your iPhone, and there are uncertified 3rd party cables.
Apple cables are very well made, but in our experience they are not the best. There are other certified cables that are less prone to breakages. So, don't automatically jump straight for an Apple cable.
USB Plug
The USB plug is probably the most important part of charging your iPhone. A lot of people think that a USB plug is the same as any USB plug. The iPhone one is the same as an iPad one, which is the same as the USB plug that charges your Bluetooth speaker for example.
iPad chargers are the best
Right up to the iPhone 7 SimplyFixIt has always recommended that people use their iPad chargers to charger their iPhone and iPad. iPhones do charge faster when you use an iPad charging plug (a 12 watt plug), rather than an iPhone charging plug (5 watts) and iPads charge a lot slower if you try to do it with an iPhone charger. So always try to use a 12 watt USB plug that can give 2amps of current to the USB cable.
Fast charging on iPhone 8
For the iPad Pro Apple introduced fast charging. By using a much stronger charging port (29 watts) and a USB-C lightning cable you can charge an iPad faster.
This was also introduced for the iPhone 8, although Apple still only provides a 5w charging plug in the box. So the official news is that if you purchase a much stronger plug - and they go up to around 87w and a USB-C lightning cable, you can charge your iPhone faster than normal.
What is the best iPhone charging plug?
The official news from Apple is that their 29w charging plug is the best for charging an iPhone. It costs £49 and you will also need to buy a USB-C Lightning cable, which costs £25 so for £74 you can charge your iPhone faster.
How much faster?
Dan Loewenherz (dwlz on Twitter) did some research and he published this graph.
It shows that a 10w or 12w charging plug charges an iPhone 8 plus up to 50% battery in around half the time that a 5w plug does. And the much larger, expensive plugs don't really make that much of a difference.
So, save your £74, buy an iPad charging plug (10w or 12w) and charge your iPhone with that. Trust me, you won't regret it.