Chianti is a simple yet complex wine.
Simple in that the primary grape is sangiovese, and simple in that all chiantis are made in a fairly large area of central Tuscany. Complex in that it can come from several different sub-regions at different quality levels — although quality levels only guarantee where the grapes come from and how the wine is made, but not necessarily a determination of how well the wine is made. Complex enough?
The basic level is chianti and chianti superiore, usually thought of as entry-level wines. The next step up is the labeling by sub-region. The most highly regarded region is Chianti Classico — more or less the geographic heart of historic Chianti — although excellent wines can be made from the other seven areas. These are Chianti Colli Fiorentini, Chianti Colli Aretini, Chianti Colli Senesi, Chianti Colline Pisane, Chianti Rufina, Chianti Montalbano, and Chianti Montespertoli.
Finally, any of these sub-regions can also have wines that are called "riservas," which mean they have more-stringent grape requirements and aging requirements, especially in the barrels. So — in theory — the best wine should be a Chianti Classico riserva, although it isn’t always.