What is the best option to enter Shenzhen from Hong Kong and vice versa? MTR or cross-border Coach?

If traveling from/to HKIA, ferry and cross-border can be your option. Ferry takes half an hour and costs 220HKD. Bus fare is 170-180HKD and the duration is two hours. If from/to downtown, MTR, ferry and coach all can be considered. Ferry: an hour, 120RMB; bus: around 100RMB and 2 hours; MTR: about 40HKD and 40min or around. In HK, you need to pay HKD, and in Shenzhen, pay RMB.