The company said its ranking is based on an analysis of expert and user opinions considering factors such as local prices, accessibility and the variety of attractions in each destination, along with traveler feedback.
"Hanoi is perfect for first-time Vietnam visitors. The country's capital offers plenty in the way of history, culture, shopping, dining and natural splendor," it said.
The company suggests that visitors try a Vietnamese coffee and stroll through Hanoi's Old Quarter to check out the Dong Xuan market, the city's largest.
Another must-do thing in Hanoi is visiting the ancient Temple of Literature, the first university in Vietnam dating back to 1070. Locals regard it as a knowledge sanctuary.
Topping the list of top 15 Asian destinations is Maldives, followed by Tokyo, Phuket and Bali.
Other destinations are Sagarmatha National Park, Hong Kong, Chiang Mai, Bangkok, Kyoto, Singapore, Jaipur, Taipei, Seoul and Railay Beach.
The U.S. Center for Disease Control and Prevention (CDC) last week dropped its "Do Not Travel" Covid-19 recommendation for about 90 international destinations including Vietnam.
Vietnam reopened international tourism on March 15, allowing quarantine-free entry and only requiring foreign visitors to present a negative Covid test result upon arrival.