If you want a 500GB SSD get the Crucial MX100.
SSD pros : much faster reading and writing, so improved loading times in games, and quicker copying files in Windows (MUCH quicker). No moving parts > longer lifespan if you don't write new files too often.
Cons : price, and basically an SSD has a finite number of rewrites in its lifespan, so if you keep deleting and writing new files on it it will die quicker than a HDD. Do not use it as cache memory in windows for this reason.
Ideal situation : use an SSD for Windows and a few games you will keep a long time, and/or that require big amounts of data to load, and an HDD for file storage and older games or games you don't plan on keeping installed for a long time.