I prefer Bosch industrial. Milwakee industrial not bad. Whatever you buy, get a tube of wormsaw grease from you. local tool dealer. Take the cover off and add about a teaspoon to the grease already there. Will run much smoother and cooler. Will extend bearing life to several sets of brushes. Makitas- up in smoke. Dewalt-shorted armatures. Ryobi and Hitachi will last a long time if you don't take them out of the box. Home improvement store grinders are a waste of time. Expect to pay upwards of 200 for a good grinder. If you think that's expensive, consider how much the lost time is going to cost.