Ranked in these QuestionsQuestion Ranking
Pro Three-way diff allows easy merging of files
Pro Highlights intraline changes
i recommend Sublimerge
Pro Built-in support for Git, Subversion and Mercurial commands
Sublimerge automatically integrates with your version control history, and lets you compare between revisions, branches, remotes, and the staging area.
Pro Can compare to clipboard contents
Con It's NOT Open Source
You can't fix or, implement nothing. And when the developer abandons the project you will be left in the lurch.
Con It's not free
Nither as free price nor as free in freedom.
Con Cannot compare text within the same file
Sublimerge can only compare entire file diffs, but not two selections within a file. Comparing within files can be useful for example, by refactoring two similar functions to use a shared function. With Sublimerge, you need to copy the sections into two new temporary tabs and compare between the two. This can be cumbersome, as if you have another untitled file, you won't be able to know which one is which.