There is a wide range of techniques that is used in the special effects industry today. These innumerable techniques have been developed and refined over the years, providing an ever-increasing sense of realism to extremely complex scenes. You have front projection, back projection, compositing, cel animation, clay animation, computer animation, camera motion control, rotoscoping, stop-motion & go-motion animation, puppetry, pyrotechnics, miniatures and model making, matte paintings, makeup, stunt and sound effects and a host of other elaborate procedures. The list keeps growing with time, and sometimes older solutions give way to newer and more sophisticated ones.
No single technique is superior to the rest, and its usage is basically determined by the specific requirements of the scene. However, some effects render more realism to the scene when compared to others and may be the preferred choice especially for certain kinds of scenes. Things like front and back projection are quite archaic and seldom used these days, but the amount of control they gave yesteryear directors to simulate outdoor shots within the confines of a studio is incalculable.
Computer generated imagery or CGI as it is known, has become the main stay of technicians these days, given the versatility of the medium. However, there still are areas in which CGI is not the most preferred solution. Whatever the advances in technology may be, the various effects techniques that have been invented over the years have each played an invaluable role in thrilling audiences of that generation. In that sense, every type of effect is a master piece.