Apple - Best replacement for MacBook Air MagSafe 2 cable (OEM or 3rd party?)
The Apple cables appear to be designed to safely melt without starting a fire in cases where the internal insulation breaks down in case of crushing, slicing, piercing (kittens are even worse than cats in this regard) or simply worn out due to repetitive bending in the same spot.
I've seen people decide to use cords when lightly damaged - sealing the cable with electrical tape. Since the voltage is low on the MagSafe side of the cord, this is more a heat/fire risk than a shock risk. The MagSafe board on the Mac usually protects your hardware from any sort of short - and it also is replaceable if it's fusing blows.
I have on rare occasion seen some nice third party adapters that work with MagSafe connections - but none yet on MagSafe 2. I have seen far, far more dangerous adapters than safe ones.
The worst part of counterfeit adapters is that they typically carry the same "safety" markings as a quality electronics adapter. Also, some have high quality plastics and similar weight so you may have to be very observant to tell a good knockoff from a genuine part. Unless you are using the adapter in an environment where a small fire could reasonably be contained without undue risk to finances or life, you might avoid using a third party adapter if you are not skilled at evaluating electronics for build quality.
- http://www.righto.com/2015/11/macbook-charger-teardown-surprising.html?m=1
The article above explains how the Apple charger is engineered with a processor in the MagSafe connector and a main processor that's equivalent to the original Macintosh - you're getting a computer inside every Apple charger as well as dense and highly safe design shown on the left and a knockoff design on the right.
I've been well served by buying Apple adapters in terms of reliability and safety, despite the higher cost. I know many that have had good luck with quality third party adapters, but wanted to explain the why some third party adapters are dangerous to use and not even close to equivalent to Apple's product.
My 2¢: Purchase OEM.
Apple's chargers (along with everything else, it may seem) are remarkably expensive, but of anything, from what I have seen, there is a reason for it. When it comes to the life-blood of the computer, charging it with something that could potentially harm the entire system is quite a risk. It would be sad to save ~$40 only to have $1000+ worth of equipment fail for some reason.
Unrelated iPhone charger review (but maybe related):
www.phonearena.com
iFixit message post:
www.ifixit.com/what-kind-of-charger
Neither of those links are very impressive, but you may find what at least some people think about Apple's chargers interesting.
For the new charger (either OEM or third party), I wouldn't worry too much about the higher wattage, unless the price is almost exactly the same, or the higher wattage unit is more available. If you purchase a Macbook Pro, it will come with a power cable as well.