I use a 5-point scoring scale. Mostly because I think that the difference between an 88 and an 89 point wine is purely academic. But to give an idea how this compares to the Wine Advocate's system:
0: equals a wine between 50 and 69 points, which is undrinkable for Robert Parker. Same for me.
1.0 - 1.5: consumable but not recommended, typically due to flaws in the wine, or simply a badly made wine. Equals 60-74.
2.0 - 2.5: Quaffable and pleasant up to really drinkable, but these are typically simpler wines. Equal to about 75-85.
3.0 - 3.5: At the bottom end, flirting with excellence; at the top end, getting to third base with excellence. 'Nuff said. Equals about 85-92
4.0 - 4.5: Undoubtedly great. At this level, I look for balance, harmony and varietal typicity, combined with the ineffable sense of place and time that mark the greatest wines. Equals 93-99.
5.0: Perfection. As of this writing, I have yet to give a full-on one (May 2011). I gave one wine a 5.0- once.
In general, I prefer wines that are balanced and harmonious and show varietal typicity. I am not a fan of overextracted wines made from artificially low yields. I am not a fanatic on biodynamic practices, selected vs. wild yeasts, organic wines or modern vinification methods. The first responsibility of wine is to be delicious, and I prefer wines with acidity and structure. Some would accuse me of being a traditionalist (a rank sentimentalist even), but I have no patience for traditionalists who excuse obvious faults as being "characteristic" of traditional wines. Defects are defects. Punto.