After a bit more thought, assuming you have to buy either a printer or a lightscribe burner:
Lightscribe:
Pros - cheaper to get a burner than a suitable printer, known costs per DVD as the process won't use up printer ink
Cons - artwork has to be simple but then that IMHO is a pro as well - less is more and all that!
Printable DVDs:
Pros - more colours available, just the excuse you are looking for if you want a new printer or all-in-one!
Cons - could use a lot of expensive ink
Stick-on labels - don't go there