Whether you're after the best graphic design software full stop, or searching for a free alternative that'll still do a great job, we've found all the top options for you here. When you're starting out, though, if having a go at a new discipline, the cost of something like an Adobe CC subscription can be prohibitively expensive, in which case you might do better with a free alternative to a pro package that has most of the features you're likely to need.
You'll be adopting a tried and tested workflow and you're unlikely to run across compatibility issues, and while the price may be high, ultimately the software should pay for itself. If you're a professional designer, stumping up for industry-standard software is pretty much the way to go.