I wouldn't actually rely on either for valid DDoS Protection, as they only protect you at a dns-level. If someone were to get the IP Address of the server that your website is hosted on (this is not difficult) then they can bypass the protection as a whole. You are best off going with a DDoS Protected hosting provider and not cutting corners if you are expecting that you might get attacked.
Consider this: Using CloudFlare or Incapsula as your primary means of DDoS Protection is like putting a lock on the front door of your home, but leaving all the windows unlocked or open to intrusion. However, as a secondary means of protection or for utilization of their CDN Feature Set then sure, they are great.