If you could only own one sander, the Festool Rotex multi-mode sander should be the one! Why? Because the Rotex is capable of operating in several modes, making it one of the most versatile sanders on the planet.
Back that up by Festool's commitment to manufacturing products of the highest level of quality backed by a three year warranty, and there's little reason not to consider adding a Rotex to your tool arsenal.
This sander has easy-to-select mode settings - rotary or random orbital - to allow you to use the sander for both aggressive and fine sanding, and polishing.