HTTPX and request and AIOHTTP

HTTPX and AIOHTTP are popular libraries in Python for sending HTTP requests. They both support asynchronous operations, but each has its own characteristics and applicable scenarios.

HTTPX is a modern HTTP client library, which not only supports asynchronous requests, but also supports synchronous requests, which makes it very similar to Python's Requests library, but provides more modern features, such as HTTP/2 support and asynchronous programming capabilities. HTTPX's API design is simple, modern and easy to use, especially for those developers who are already familiar with the requests library. In addition, HTTPX also supports streaming response, TLS support, custom headers and authentication, and JSON/XML serialization.

AIOHTTP is an asynchronous HTTP client/server framework, which provides non-blocking I/O operation by using asyncio module, and is very suitable for applications that need to handle a large number of concurrent connections. AIOHTTP was built for asynchronous operation from the beginning, and it does not support synchronous programming. This library can be used not only as a client, but also as a server, supporting middleware, signaling and custom routing, which is very suitable for writing small and extensible Web servers.

In terms of performance, AIOHTTP performs better in handling a large number of requests. For example, in the test of sending 1000 asynchronous requests, AIOHTTP is about 6.43 seconds faster than HTTPX. However, for a small number of requests, there is little difference in performance between them. 

Which library to choose depends on your specific needs. If you need a library that supports synchronous and asynchronous operations and want to have a concise and modern API, then HTTPX may be a better choice. If your project needs to handle a large number of concurrent requests, and you only need asynchronous operations, then AIOHTTP may be more suitable for your needs.