KDiff3's feature you'll love if you do a lot of merges
KDiff3 is a tool I'm using for merging conflicts. I tried Meld, vimdiff and other tools earlier, but kdiff3 is really make you stop looking for another one.
Have you ever seen how diff and other tools make wrong code blocks alignment choices and compare apples to oranges. It always happens. You move a block of code, for example block in if-elsif chain and diff tool goes crazy and think that you've changed code, shows you a lot of crap.
You can forget about this nightmare. KDiff3 has "Add Manual Diff Alignment (Ctrl+Y)" feature. You select line in one file and press Ctrl+Y and do the same in another view. KDiff3 aligns marks. That's all, after that you see beautiful diff. All blocks in their own place, just plain add/remove differences. You just selecting A/B[/C] choices. Work's done.