I'll echo what Cosmo said. There are a lot of good designers out there but their production skills are atrocious. No bleeds being the biggest right next to really uh...novel... use of color palettes....
Both sites are equal in regards to providing high-quality professional imagery. The question you need to ask yourself is what size images you’ll need.
A Photos.com subscription provides you with 170,000+ images that come in 3 different sizes (up to 16MB). You’ll find that they’re plenty big enough for all Web and most print projects. So, unless you need really big images, this would be the way to go. Plus, if you do occasionally find that you need even bigger images, Photos.com provides the additional feature of a super-resolution pay-per-download option.
An AbleStock.com subscription offers you 100,000+ super-high resolution images. In other words, they have BIG images. So, if you have a lot of projects for which you need really big images then AbleStock is the way to go.
Both sites offer free samples. I'd suggest downloading a sample or two from each site to see which is the best fit for your needs.