A promising clone that's already produced a fair number of results for me; N. boschiana BE-3448 has in the past produced pitchers that deepen to incredible shades of burgundy and rust, the peristome semi-striped but often aging to solid black cherry. This is a female plant, with one cross already produced (x merrilliana x campanulata) and hopefully many more to come!
N. boschiana is a primarily highland species native to Mt. Besar and Sakumbang in southern Borneo, with pitchers that can reach nearly a foot in length. I've found it to be fairly easy to grow so long as the soil is kept properly moist and well-aerated, and it gets a lot of light. It sulks somewhat during summer (funny though, this is the largest pitcher yet and it's August!), preferring the cooler intermediate conditions it receives in winter.