Lavender or Porcelain?
Go with Lavender (self blue) is a recognized variety. You can improve the type of lavenders with blacks, though lavenders have come a long way in just a couple years and are improving by leaps and bounds.
Porcelain is an AOV and there is no written standard for the breed, it is not a color I'd suggest a first timer to work on until you've gotten your foot in the water with another color. Porcelain will be a great 2nd color because you can use lavender to cross Porcelain birds back to. Most porcelains are still in the development stage, they are still a very wide variety of shades and color differences out there.
Blacks are a great color to work on, nowadays its gotten so dilute (people using them in BBS pens then breeding the black offspring back around to get blacks that aren't 'pure' and true black anymore) Breed Black to black, weed out color in the hackles. There are many good breeders out there for blacks, so you'll have an easier time coming across black birds.