Traditionally, people always drank red wine with red meat - beef, venison etc., and white wine with white meat and fish, which would include pork. These days, only wine snobs bother being so colour-coordinated, so the best wine to have with pork is the one you enjoy drinking! If you have guests, have a bottle of each, and let people choose what they like, although white wine is the preferred choice for most people.
Although not an expert on wines, I've enjoyed a great deal of roast pork over the years. On the basis of that, I would recommend a hearty Chardonnay or Sauvignon Blanc. Red wines tend to be heartier and more acidic, qualities that can overpower delicately flavoured meats such as pork. On the other hand, lightly flavored whites will be completely lost behind, say, pork with a mustard sauce or something similarly hearty. Cheers!