The Samsung and Asus are basically similar in specs. Not sure about Samsung, but I have read many bad complaints about Asus support. Asus products are overall good quality, if you fall from hardware heaven (meaning your laptop develops a problem), then you need to deal with customer support from hell.
The Lenovo is an ultrabook so the CPU is a bit slow, but it does consume less power. It is also the lightest of the three laptops so if you are going to lug around a laptop you might want to take weight into consideration. Tech support is generally at the very least average, but I don't think it will go beyond "good". However, support for their business oriented laptops (i.e. ThinkPads) are at least good and you can probably expect it to be excellent in general.