It’s fortunate for people who keep kosher that there was no commandment against coveting thy neighbors wine. Only a tiny fraction of all wine released is kosher. Much of the kosher wine that is sold does not provide a drinking experience which is entirely positive, let alone similar to that of the best non-kosher wines. And the availability of terroir-reflective wines, which many of us take for granted, is almost nil when it comes to kosher bottlings.
The good news is that some dedicated people are trying to change this. For example, Covenant Wines is focused on providing top notch Napa Valley Cabernet Sauvignon that is kosher. We recently purchased a bottle each of their two 2006 releases to try.