That's a tough question, as they are all great players and all Editors' Choice winners. One thing you'll definitely want is a compatible armband so that your wife can have her hands free while working out. But that doesn't narrow things down much, because all the players you name have optional armbands that you can purchase (however, the iPod Nano has the most choices in this area).

The benefits of the Nano include its excellent relationship with the iTunes software and its sleek and sexy design. However, this player also has the fewest features and sound-enhancement options, such as a user-adjustable EQ setting. Plus, I personally think that it doesn't quite match the sound quality of the other two, though this difference is negligible. The iRiver Clix has a cool and unique design, offers plenty of features, such as an FM tuner and video capability, and it has the largest screen of the bunch. On the other hand, it's the largest player (though not by much), and it's not the easiest to control with just one hand. Finally, we have the Zen V Plus, which is probably what I'd recommend in this case, if only because the joystick makes it very easy to operate while the player is strapped to your arm. It has other things going for it, too, such as excellent sound quality, FM radio, and audio recording capability.