Well :
Normal mapping, specular , water, glow ,refraction
HDR, bloom , mtion blurr , colored vision (night googles,infra red etc ...)
are the standard main ones you need !

No need to learn shader , with theses standard you can already make great games,
and AAA games uses theses.
With normal map /specular you'll have a next gen look :
illusion of very detailled models !

Some 3D engines give you all theses shaders ready to use and apply to your models !

Wait 3DGS to evolve in shaders, or if you can't wait one more year ,
buy another 3D engine now ?