Dell netbooks have the worst keyboard (even though it's got big keys) and worst trackpad. The design is very "Dell", cheap looking/feeling and bad build quality. I suppose they tried to make up for it with designs, colors, etc but the netbook inside is just junk.
HP netbooks feel like a big rock, it's way too heavy for some reason and the trackpad is weird with the side left/right click buttons. The keyboard, also has big keys, but very hard to type on.
I don't like the Toshiba ones because the power button is awkwardly placed. Keyboard is average for netbooks and overall feels like it ripped off the designs of other netbooks and hastily slapped it together.
Either the Lenovo S10-2 or the Acer AspireOne AOD250. I really like the Acer (I have one) because of the solid build quality, really good keyboard and trackpad. It's really lightweight, compared to the HP, and the webcam is surprising good quality, even in low lighting conditions (I tested this on Asus, Acer, HP, and Lenovo netbooks). The design is the best I've seen on a $300 netbook (the more expensive HP w/ ION graphics is the best 'netbook' but it's over $300) and feels really nice. The top part that goes around the keyboard, trackpad, etc is one piece of metal.