This article is from the WineMaking FAQ, by malak@CAM.ORG (Don Buchan) with numerous contributions by others.
Kits vary in quality, usually according to price: The more expensive it
is, the better the quality.
When buying kits, don't buy a cheap one just to minimize your financial
risk. Cheap wine kits might resemble watery grape juice with fire in
them (while some are really good). An expensive kit uses the same
principles, but the product is usually far superior. Experiment; often,
paying a premium pays off. Look for a kit that has a lot of concentrate.
The ideal would be a concentrate that has 16 litres (3.5 imp. gal.; 4.25
USG) of concentrate. The next best would be about 10 kg (22 lbs).
Some people swear by kits, while others by fresh juice. As a steady
rule, high quality wine that lasts for decades is made from high
quality fresh juice from fruit that was grown and picked under optimum
That being said, there are good kits of great quality that can beat
some fresh juice wines, but usually only the more expensive kits vs.
Experiment and decide for yourself what you want. What YOU like as a
final product is the most important factor, as well as the commitment
you wish to make.