DiffMerge is a powerful, cross-platform application that allows software developers to compare, merge, and synchronize files and folders quickly and easily. It is an ideal tool for developers who are working in a distributed environment and need to keep their files and folders synchronized. DiffMerge can compare and merge text, images, and binary files, as well as synchronize entire directories. It also has powerful features such as 3-way merging, line number display, auto-merge, and syntax highlighting. DiffMerge provides a visual, intuitive interface that makes it easy to compare files, review changes, and merge files without confusion. It is available for Windows, Mac OS X, and Linux operating systems.
Better handling of Unicode than discontinued DiffMerge.
I like to compare, but I still can't say if this is the best because I didn't try the others.
Worked with it for years. very solid.
Covers all functions, has a very nice user interface and is open source compared to other commercial alternatives (Beyond comparison).