The POÄNG armchair from IKEA is extremely comfortable, and, at only $79, is a fraction of the price of a LeCorbusier LcFour:
There's a matching footstool, too.
User testimonial: The way this chair supports you under the knees, taking the weight off your feet, is blissful. Due to the wooden construction, the chair can also flex slightly, meaning it adjusts to you as you settle into it. Simply the best chair for sitting on with a LaptopComputer that I've ever tried. -- EarleMartin