9 of the best World Cruises in 2020 and 2021 Best for in-depth exploration: Seabourn. The lovely 450-guest Seabourn Sojourn starts her 146-day World Cruise in January 2020. Best for value: Crystal Cruises. Best for continent collectors: Silversea. Best for long duration: Oceania Cruises. Best for British tradition: Cunard. Best for Scandi chic: Viking Ocean Cruises.