Arguments for Open Access
The more people who have access to the research results, the more useful it becomes.
By removing the barriers to accessing a publication, more people can access them. Many institutions, and particularly low-resource institutions in the third world are unable to access traditional journals due to the high subscription prices.
The process from accepting your article to publishing it can be accelerated
If you publish your research in Open Access, you can normally self-archive as soon as your publication is accepted and in some cases even earlier. The publishing process is thereby faster and your research can be used earlier by your colleagues. Today, many publishers allows the author to immediately publish a copy of the adopted article in an open archive.
Your article may be read by more people and cited more often
There are indications that open access articles are read by more people and cited more frequently.
By publishing in Open Access journals, you have greater control of the material
You do not sign your copyright to the publisher and have greater control of how you want to use it. If you want it in your teaching, etc.
Research that is partially financed with tax credits should benefit everyone
Most of the traditional journals has high subscription fees and charge high profits. This has led to the absurd situation that universities and colleges have to pay through subscription fees in order to gain access to the results of the research that they themselves have funded. During Open Access publishing, everyone can access the research results.
Eysenbach G (2006) Citation Advantage of Open Access Articles. PLOS Biology 4(5): e157. https://doi.org/10.1371/journal.pbio.0040157