I've hardly ever used anything other than Meld. Can you recommend anything else?
It would be extra nice if you give a reason for your recommendation (as a Comment).
[note] I want an alternative because Meld has recently lost the feature to copy entire contents from one file to another. I'm referring to the functionality available via the Copy To Left/Right right-click menu item.
[update] I just checked, and the problem was introduced by 1.3.2. 1.3.1 works well, and the latest I've checked is 1.4.0, and it doesn't work.
Best Answer
There are a number of tools that are usable:
Do you have two files and want to view their differences? Use a "file difference viewer". Do you have a diff file and want to look at it in an easy-to-read display? Use a "diff file viewer".