dell has the best support if you are the type to need it. asus support is an answering machine. lenovo has average support.
if you need or want to replace the drive on the dell you will need to almost completely take apart the laptop to get to the drive.
the lenovo has a super loud dvd drive but you can set it to quiet mode in the bios which fixes it at the cost of speed.
couldnt find the exact asus laptop but people complain about the screen looking like poo on the models that are nearly the same. i bet they use the same screen.