Determining the "best" part of the Amazon Rainforest can be subjective and depends on what you're interested in experiencing. Here are a few notable regions within the Amazon that are renowned for their unique features and accessibility:

Manaus, Brazil: Often considered the gateway to the Amazon, Manaus offers a wide variety of tours into the rainforest. The nearby "Meeting of Waters," where the Rio Negro and the Amazon River meet but do not mix, is a spectacular natural phenomenon.

Iquitos, Peru: As the largest city in the world not accessible by road, Iquitos offers a unique perch from which to explore the northern Amazon. The city is a launch point for many river cruises and excursions into the surrounding rainforest

Madre de Dios, Peru: This region is known for its biodiversity and is home to several eco-lodges and natural reserves like Tambopata National Reserve and Manu National Park, where you can experience diverse wildlife and lush rainforest.

Ecuadorian Amazon (Yasuni National Park): Yasuni is recognized as one of the most biologically diverse areas on the planet. It offers opportunities for wildlife viewing, and cultural experiences with indigenous communities.

Rurrenabaque, Bolivia: Serving as a gateway to the Bolivian Amazon, this town offers access to both the Pampas and the more forested jungle areas of Madidi National Park, which is noted for its incredible biodiversity.

Leticia, Colombia: The southernmost town in Colombia, Leticia is located near the borders of Brazil and Peru. It's a great starting point for exploring the Amazon and is known for its cultural tours and boat excursions.

Each of these locations offers a unique Amazon experience, so choosing the "best" one depends on your interests, such as wildlife viewing, cultural encounters with indigenous peoples, or adventurous eco-tourism activities.