There isn't one, because every person and every couple are different. Also, I don't believe in perfection.
For some it might be the candlelit dinner; others a film and popcorn; others ice-skating; others a walk along the beach; others a hike; others a trip to the fair; others going to or taking part in some kind of sport; others a trip to the art gallery; etc. etc. etc. etc. etc.
What can make it seem perfect, what really matters is that at the end of it the people have had a lovely time, have felt at ease, have felt comfortable, have really enjoyed themselves - even if it's the only date they have, to come away having enjoyed their time together is, what I think, makes it 'perfect'.