No, don't use an angle grinder, the disc is too small (usually less than 5" in diameter) and the RPM is too fast... Angle grinders are used to cut metal and stuff... usually at around 5-12K RPM, whereas your paint can only withstand up to 1700RPM tops... even at 1000RPM you can burn through paint...

Keep this rule in mind... if you can't polish your paint well with your hands, using a power tool won't help you. It's like asking a blind guy to wear eyeglasses so he can read better... it won't help.

Stick with a random orbital if you are looking for a tool.