Recs.
Updated
Layer-based 3d painting software that can paint full PBR materials with ease with immediate feedback. Designed with texturing for video game and other computer graphic projects.
Specs
Pros
Pro Flexible texture export options
You can export textures from Substance Painter in preset configurations targeting other 3d software or make a configuration for your needs. You can setup naming conventions and even pack texture maps into individual RGB channels. You can also add texture padding on export as well.
Pro Allows you to paint in full 3D
Since Substance Painter allows users to paint in full 3D, it can be used not only to paint full textures, but can also paint masks which can then be used in other tools (like Substance Designer) for material filter generators (like the ones used to make edge wear and dirt).
Cons
Con Expensive and impossible to run without an expensive graphics card
The free trial is the only thing free. You'll have to pay a lot of money for the full version, and even if you do get it, you will have to pay for an expensive graphics card to use it, which means a lot more money flying out of your wallet and/or bank account.
Con Cannot export Substance SBSAR files
Unlike it's counterpart Substance Designer, you cannot export .sbsar files using Substance Painter. It is designed solely as a texture painting application and not a procedual one, despite leveraging Substances for procedual generation of details.