As for the quality, I would imagine that it would stem directly from the seeds that were used to grow a certain type of tobacco and differences in soil between that of Cuba, the DR or Nicaragua. Also another factor that might significantly change the taste of the cigar is aging. Aging, besides the seed and location, is what smooths out and often changes the taste of the tobacco.
I guess to answer your question, you will be paying higher for quality aged tobacco than you will for cheaper tobacco. However that does not mean the cigar will be more smooth.
What I would recommend is to read reviews on the cigars that you are trying, and find with which filler and wrapper you most enjoy. You may notice that you have a natural preference towards cigars from the Nicaragua (such as Padron) over stronger Ligero cigars grown by La Flor Dominicana in the Dominican Republic (for example). It's important to find out what you like, because mild is often a term I find a lot of people use based on their own cigar smoking context.
One last thing to keep in mind, the color of the wrapper does not always coincide with the strength.
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