Here is my experience using both providers for pull zones only.
I started using CDN pull zones for my websites on December 31, 2012. I did some research and MaxCDN provided the features I needed at the best price. I signed up for one of their yearly plans and I setup my sites to use the CDN for everything except the page itself. Using Pingdom's page test, the load times were 2-3x quicker, every single time.
Anyway, I was happy for 11 months until Dec 5, 2013 @ 4:40pm when I got an email saying my MaxCDN account is suspended. If I have any unpaid invoices I should pay them to avoid any service interruption. I frantically tried to load my websites that use MaxCDN's pull zones. None of the sites showed more than a blank page. I quickly disabled the CDN and all sites loaded normally again. It worries me that I may have not been at the computer when this incident occurred. I proceeded to log-in to the control panel. I had no unpaid invoices and 1.97 TB of bandwidth available! So I called them. The gentleman on the phone apologized for the inconvenience. He said he will immediately follow up with the correct department to make sure my service is unsuspended then email me to let me know. Also, there will be an investigation into the glitch that occurred in their system.
Another disadvantage with MaxCDN's basic package is their limit of two pull zones. If you want to use the bandwidth you paid for on an additional site, you will have to shell out an extra $12/year/site.
After some research I learned about several new offerings in the market. CDNify suited me best so I signed up on December 5, 2013. What I like most about CDNify is not being charged for, or restricted to, the number of pull zones used with your bandwidth.
Most important, using the Pingdom page test as a measure of speed, my pages loaded equally fast when using the more cost effective CDNify.
Well, I hope this is helpful for anyone considering CDNify.
Well, CDNify is phasing out their pay as you go CDN and I have about 6 months left to find a new provider. I use ~1.5 GB/month and save about 1-3 seconds on the initial page load depending on how far away the end user is. The only reason I think I should be using a CDN is to help with my search rank. The sites are articles and photos and are not really used to generate revenue, although 90% of visitors every month are new and mostly from Google.
I haven't done much research yet, but it appears Amazon Cloudfront offers SSL using SNI at no significant cost when compared to using a dedicated IP for $600. Last December, when I tested Cloudfront, page speed tests showed more of a delay when loading content compared to CDNify or MaxCDN.
Yes there are a bunch of different CDN platforms out there like ******, CDN.net, CDN77, and the list goes, but they're all based on one network: OnApp.
Hussein raised some good points, but honestly it comes down to what you need from a CDN, either if it's video on demand, static content, small data usage, large data usage, POP locations, etc. There are CDNs out there covering each niche, which is great for consumers as they're not limited to a single provider.
Before committing to a CDN, do some research and see if it meets your needs in terms of features, costs, and anything else in between. I actually work for CDNify, but we try to focus on handling static content for developers, startups, and agencies as it's what we do best.
Hopefully I've cleared a few things up, but again it's all about finding the right provider that fits your needs, and with some many on the market you're really spoilt for choice