If you want to see Bran Castle ( Dracula Castle) , Rasnov Citadel and Few of the Fortified Churches I reccomend you rent a car and drive to those places. Would be of a great use to you, if you would consult a map. read more
If you are asking as a tourist, take the train from Gara de Nord. The scenery is worth it - it might take half an hour to an hour more than a modern bus, but the views as you cross the mountains are worth it. read more
The cheapest way to get from Bucharest to Transylvania costs only 84 lei, and the quickest way takes just 5¾ hours. Find the travel option that best suits you. read more