What is the best source code editor and why is it the best?
I like Atom. It's the editor I use every day.
Is it the best? That's hard to say. But it has a lot of benefits:
1) Free!
So definitely value for money!
2) Open source.
So if you're interested you can check what it's doing under the hood. But perhaps more importantly there's a lot of open source people in the community that can help with any issues.
3) Customisable.
There are lots of add-ons that are also free. Linters to keep your code neat. And colour schemes, which are actually really useful in (a) checking syntax and (b) avoiding eye strain.
4) Simple design.
I find Atom pretty intuitive and simple to use.
All around a pretty good package. Maybe if you're looking for something for professional usage there are better options but for everything I've done so far Atom has worked really well.