DAX (Data Analysis Expressions) is a formula language used in Power BI, Analysis Services, and Power Pivot in Excel. While Power Fx is designed for low-code platforms, DAX is more suited for data analysis and reporting, serving a similar purpose of data manipulation using expressions, making it a competitor in terms of data expression languages within the Microsoft ecosystem, although serving different purposes and products.

JavaScript is a widely used scripting language for web development. It is a competitor to Power Fx in the sense that it is another way to write logic, particularly client-side logic, but requires much more code and a different skill set.

C# is a general-purpose programming language. It can be used to create more complex applications than those typically built with Power Fx. It is more complex, but can perform some of the same tasks, in that it can be used to write application logic.

VBA (Visual Basic for Applications) is a scripting language used within Microsoft Office applications. It is a competitor in the sense that it is another way to write logic within Microsoft applications, but is being deprecated.