NOT ALL WEBSITES SHOULD USE A CDN
If your target group is not all over the world. Forget about using a CDN, it's a waste of money.
WHAT CDN SHOULD YOU CHOOSE?
You need to compare the different CDN'S on 3 parameters, amount of servers, price point and whether they integrate with your current setup or not.
IS CLOUDFLARE THE BEST OPTION?
It depends on your needs. Cloudflare is the CDN with most servers around the world, but it also comes with a big price tag.