Welcome to the forums!
My species that I would pick outthat would be superb beginning plants would be the following:
N. truncata- a large grower after quite some time but relatively small when young and slow growing. Can tolerate low humidity but does best with 60% and higher humidity.
N. sanguniea- nice easy plant, appreaciates a terrarium
N. khasiana- extremely adaptable plant, excellent on the windowsill.
N. ventricosa- very adapable but appreaciates a little bit of misting and decent humidity, 50% and more.
N. alata- easy species requiring a terrarium for good pitcher production.
N. x ventrata- natural hybrid, N. alata x N. ventricosa, it is very adaptable like N. khasiana
N. gracilis- good for a very humid and warm (70F and more) terrarium.
N. rafflesiana- also good for a sealed terrarium and like N. gracilis, it appreaciates warm and nice humid conditions.
N. gracilis, N. rafflesiana, and N. ventricosa are available from this site also, just go to thier online catalog and go to nepenthes.
Good growing!