I'm an amateur photographer and retired real estate agent. I am thinking of starting a real estate photography business. Can you tell me what is a good starter editing software, but not a monthly subscription? Cyberlink, Photodirector, and Lightroom were recommended.
I think Lightroom is the best way to edit for any beginning real estate photographer. You can still get a non-subscription version of Lightroom 6, although the subscription version of Lightroom has many more important features.
The reason that Lightroom is better for real estate photographers than the huge number of other options out there is Lightroom's superior lens correction features. Lightroom has lens profiles for most lenses that real estate photographers use and can remove vignetting, barrel distortion, and chromatic aberrations, as well as straighten verticals quickly and easily. All these fixes are a big part of what real estate photographers do in post-processing. Many of the other photo editors don't have lens correction or lens profiles (like Photodirector) for all lenses.
Another big reason to use Lightroom is the huge amount of online training both on YouTube and training that you can pay for at places like Lynda.com.
For those ideologically opposed to subscription software, Luminar has much of the functionality of Lightroom and can be used as a Lightroom plugin to do layer blending and quick adjustments.
I like to end with an argument for the $9.99/mo Creative Cloud Photography plan. I've been a Photoshop user since the 90's and I'm totally convinced that both Lightroom and Photoshop are the best you can get for professional photo editing. So if you are going to be a professional real estate photographer, you are eventually going to want to use both Lightroom and Photoshop. There are tons of other alternatives these days but they don't come close to Lightroom and Photoshop.