As with everything in life, air compressors come with different brands to make them recognisable. Different brands are known for different things, so it might be that it helps you to differentiate between different kinds of compressors. For example, one brand may specialise in rotary screw compressors, and another might specialise in environmentally friendly compressors that do not run on lots of dirty fuel. Once you have got to know a brand and what they do, you will easily be able to identify if their products are what you are looking for. 

If you choose a major brand, you are much more likely to get a good guarantee as well. You air compressor will usually come with a parts guarantee, so that anything which ceases to work can be fixed or replaced. 

You will also get better service, as suppliers will know a lot about branded air compressors and will be able to share their knowledge.