If your path is to sculpt art then you will need a 4 1/2" angle grinder, a straight grinder, and a flex shaft grinder. On each of the 3 tools I can change out bits, disks, wheels, and brushes giving me a variety of ways I can use each.

The reason behind having both larger and smaller grinders is to have the ability to artfully use both 1/4" and 1/8" burr bits, disks, and brushes. Many 1/4" straight shaft grinders come with 1/8" collets however I find there is a lack of control with the larger tool and a smaller bit. Your hands are further away from the bit giving you less control and the higher RPM isn't isn't good for small bits. When you use the 1/8" bits in the flex shaft grinder your hands are closer to your work allowing you to achieve precision with enough practice. 

I sculpt all that you see me create today using these 3 tools. (I have 3 angle grinders, 2 straight grinders, and 2 flex shaft grinders all set up with different bits, wheels, bits, and disks to save time as I sculpt.)

The tools can be found in a wide price ranges. I've found some cheaper tools preform just as reliably as name brands, however it's hit and miss and you usually get what you pay for. Having quality tools that run smooth will help you achieve smoother work, however its' practice that will give you the skills, not fancy tools!