The 510 is regarded as the best in speed and reliability. All Intel SSDs are rated highly for reliability. The 520 is a SATA III compared to the SATA II 320. It is probably cheaper because of economies of scale in production.
Since you are a gamer and do some work you can rule out the Intel 710. The 710 is an enterprise class ssd designed for business and professional applications.
You mentioned editing. What do you edit? documents, images, or videos?