Well that would depend on what you are using it for...
For the casual camper/car camper: a cheap Walmart/outdoors brand such as Coleman, Kelty, etc.
For a hiker or backpacker: North Face, Marmot, MSR, and Big Agnes (and others) all make great lightweight tents for reasonable prices with good features and quality
For intense winter camping or mountaineering: Nemo and Mountain Hardwear make high quality, reliable, and lightweight tents for extreme conditions. Personally, I believe that these two brands far surpass The North Face in this area. They tend to be much lighter and have better mountaineering features.
Of course, the best thing to do is look through as many tents and brands as you can find and match up the features, weight, and price to what suits your needs. This will be different very each person and will often vary from trip to trip and year to year.