I agree with Albert. Photoshop/Lightroom are worth the money. My subscription costs $11/month for Photoshop, Lightroom Classic CC and Lightroom CC. It includes 20 GB of online storage at that price. I have not used GIMP. While it is free, I doubt it can match the combination of PS and LR for File Management, Processing, and all of the rest that LR Classic is able to do.
Note: as of May 5, 2019 the 9.99 plus tax subscription (which is a total of $11/month in Seattle) may not be shown upfront on the Adobe website. If that is the case, dig deeper, or call the Adobe Customer Service number and ask specifically for the Photography plan with only 20GB cloud storage. If you prefer to use more space on the cloud, that is available for more $ per month. Also, note there are now TWO Lightroom softwares, the CLASSIC CC, and the CC. While they can be used in tandem, there is a steep learning curve if you are unfamiliar with your operating system and file/folder hierarchy. I highly recommend becoming familiar with the CLASSIC CC version first.