Well, it really depends on how much money you wantto spend. OEM's of course are better but much more expensive. The HID conversion kits are reasonable and are much better than regular halogen. I'm running the 4300K HID conversion kit and really like it. You should expect to pay around $800-$1,000 to covert over to the OEM HID's and an HID conversion kit will run you about $400-$500 depending on color.
One other thing to consider is that all HID conversion kits that are not OEM are considered illegal by DOT and are not suppose to be used on the roads. I sell the HID conversion kits but I also have a disclaimer stating that it is not legal unless they are used off road. I'm not trying to persuade you one way or the other but just wanted you to know the facts.