You don't want to wake each morning in a shelter covered with condensation that will shower you at the least provocation. In better quality tents, some of the ventilation is provided by mosquito netting. Poles are also a major consideration. Many inexpensive tents have a poor grade aluminum alloy pole prone to collapse if bumped or if winds are high. Many tents, particularly domes and their variations, come with fibreglass poles.
Hollow poles tend to be better than solid ones.
Poorer quality tents often have ties or other closing devices instead, and these alternatives are all but useless in wind and rain. Ensure that zippers are of good quality and work smoothly. If not, chances are you will have to replace them in the near future. Workmanship is what really separates the wheat from the chaff in tents. Once you could associate a name with a particular design and quality of tent.