Cutter

R2, or Radare2, is a complex framework for reverse engineering and binary analysis. To be more precise, it's a command-line tool built around a disassembler, and it supports a wide range of executable formats for various OSes and processor architectures.
If you want to make the most out of this framework, but don't want to deal with the usage of the command-line, then you can give Cutter a quick try.
In short, Cutter is a QT and C++-based GUI for Radare2. It's to make the whole framework a lot more manageable for the average user, and best of all, it's free and open-source.

Cutter's feature set

One of the most important features of Cutter is the fully integrated Ghidra decompiler. The decompiler is responsible for analyzing binaries while providing the end-user with a high-level representation of the machine code within it.
To put it in a more approachable form, it reconstructs the source code from which the binary was compiled in the first place.
The application also boasts a debugger for dynamic analysis, a disassembler, a hex editor, a Python scripting engine, plug-in support (great for extending the app's functionality), and all the necessary tools for emulation (both crypto algorithms and malware analysis included).

Unexpectedly competent GUI

First of all, it's worth noting that Cutter is created using Qt and C++. The GUI is quite modern, boasting a lot of useful touches. For example, it has four integrated themes (Light, Native, Dark and Midnight) that can be customized using the built-in theme editor.
There are also various widgets aimed at making the whole user experience better.

Conclusion

Taking everything into account, Cutter is a well-executed, modern-looking, and easy-to-use reverse engineering tool. It's free and open-source, and it runs on all major OSes such as Windows, macOS, and Linux.