See January 2004 Consumer's Reports ratings of sanders for performance, features and specific details. Ratings are based on speed by type, controls, dust capture, handling, and noise. Within types, listed in order of overall score.
----- RANDOM-ORBIT Most versatile; 5-inch-diameter can handle some rough-and most finish-sanding.
Craftsman (Sears) 27957 DeWalt DW423K Makita BO5012K Ryobi RS241 (CR Best Buy) Porter Cable Quicksand 333 Craftsman (Sears) 11623
----- FINISHING Good for corners; 1/3-sheet models are best for larger areas.
Makita BO3700 (1/3-sheet) DeWalt DW411K Porter Cable 340K Black & Decker FS350 (1/3-sheet) Craftsman (Sears) 11632 (1/3-sheet) Black & Decker FS500 (CR Best Buy) Makita BO4552K Skil 7230 Craftsman (Sears) 11627
----- DETAIL Strictly for finish-sanding tight corners; you'll need a random-orbit or finishing sander for most other work.
Ryobi CFS1500K Cat Craftsman (Sears) 11680 Mouse
----- BELT Best for quickly sanding large or uneven surfaces; not meant for finishing or extended overhead sanding.
Porter Cable 352VS Makita 9911 Skil 7313 Ryobi BE318 Black & Decker BR400