As you can imagine, any discussion of quality in pianos is likely to involve a lot of subjectivity and be somewhat controversial. However, a useful generalization for the purpose of discussing quality can be had by dividing pianos into two types: performance-grade and consumer-grade. Performance-grade pianos are made to a single, high quality standard, usually in relatively small quantities, by companies that strongly favor quality considerations over cost. Consumer-grade pianos, on the other hand, are built to be sold at a particular price, and the design, materials, and level of workmanship are chosen to fit that price. Most consumer-grade pianos are mass-produced at a variety of price levels, with materials and designs chosen accordingly. Throughout much of the 20th century, the United States produced both types of piano in abundance. At the present time, however, most performance-grade pianos are made in Europe and the United States, while virtually all consumer-grade pianos are made in Asia. Due to globalization and other factors, the distinction between the two types of piano is beginning to blur. This is discussed at greater length in the article "The New-Piano Market Today," elsewhere in this issue.
The above explanation of quality in pianos is very general, and some aspects of quality may be more applicable to your situation than others. Therefore, it pays to take some time to consider exactly what you expect from your piano, both practically and in terms of lifestyle. Practical needs include, among others, the level of expressiveness you require in the piano's tone and touch, how long you want the instrument to last or intend to keep it, and what furniture it must match — as well as certain functional considerations, such as whether you use the middle pedal, desire a fallboard (key cover) that closes slowly, or need to be able to lock the piano. Lifestyle needs are those that involve the prestige or artistic value of the instrument, and how ownership of it makes you feel or makes you appear to others. Just as a casual driver may own a Mercedes, or one devoid of artistic abilities may own great works of art, many who don't play a note purchase expensive pianos for their artistic and prestige value.
A couple of the practical considerations require further discussion. Concerning expressiveness: What kind of music do you play or aspire to play? One can play any kind of music on any piano. However, some pianos seem better suited in tone and touch than other kinds to some kinds of music. Quality in piano tone is often defined in terms of the instrument's ability to excel at pleasing players of so-called "classical" music because this kind of music tends to make the greatest expressive demands on an instrument. So if you aspire to play classical music seriously, you may wish to one day own a fine instrument capable of the nuanced tone and touch the music demands. On the other hand, if classical music isn't your thing, you can probably get away with a much less expensive instrument.