First of all, you state that you do use "cooking wines". I wish you would clarify that for us. If you mean the bottles in the grocery store that specifically state on the label "cooking wine", then I would say immediately toss those to the curb! The typical "cooking" wine is loaded with preservatives and salt and quite literally they are not "fit to drink!"
IF YOU CANNOT DRINK IT FROM THE BOTTLE, THEN IT IS NOT FIT TO COOK WITH!
Sorry for screaming, but this is so important for people to know! I am passionate about cooking and wine and I tend to get on a soapbox over my fury at the food industry's adulteration of our food supply!
I have studied about wine for years and have to say that you can never learn enough! This is one area that is truly, each to his own! There is such a variety of quality, affordable wine on the market these days that it is hard to narrow the choices.
However, there are some commonalities that most producers try to adhere to when marketing a particular variety or "style." You must decide if you are in the market for light and fruity with some residual sugar, medium body with a slight tannin (the "bite" in young reds,) or deep and concentrated flavors with the very characterisitic dry, almost astringent after-effect (note-I never say "after-taste, because taste is such a subjective term!).
Your best bet is to try experimenting with a few wines and find out if there are any tasting clubs in your area. I wish you many "good tastes" in your adventure!
As far as the cholesterol issue, there are many NATURAL ways to reduce LDL cholesterol, while increasing HDL! I am a nutritional advisor and herbalist, so if you are interested in more info then feel free to send me a private email. I think a detailed response here would be very long winded and very off-topic