first thing's first...differences between the sleek and the touch. i have a sleek and bought a touch when it first came out last year.
the touch is a massive brick compared tp the sleek. as its name implieds, the sleek is very thin, smooth, and nice to look at. unfortunately, the sleek has no select button, just touching the center of the scrollpad, but the touch has an "OK" button. fairly handy.
battery life on the touch ousts the sleek by about 6 hours, at least from the manufacturer. the sleek has an alarm clock and some other nifty features not included on the touch.
the touch feels less likely to get scratched and has a designated "Random play all" button, though i never used it.
the one thing i will say i dont like about the sleek is the connecter form. it has a docking station on the bottom, and thats the only jack except the one for the headphones. the power supply and the usb use this connector. when plugging in the power adapter, it gets slightly confusing, but such is life.
personally, i like the sleek better, cause its smaller and sounds better, but the touch can be found to up to $30 cheaper. but the sleek is at best buy, so i like being able to go right to the store if i need to.
AS FOR THE COWON....
I was actually going to get this to replace my iPod. i loved everything about it. it had everything the ipod did, plus more, for the same price. wasn't so keen on the joystick, but whatever. doesnt matter too much. problem was at the time, the player didn't support ID3 tags, so i couldnt view by artist. thats why i didnt get it. few days after i spent $40 on various things, Cowon released a firmware update, and now the player supports video!!!! RAR!! my luck. but i have heard nothing but good things about this device from users. screen seems a little small for movies, but is probably fine for personal viewing.
hope this helps 