Among my personal favoutite things about emacs are

• the query replace functions
• ediff (I can't say eough good things about this) - lets you do interactive diffs/merges on 2 or three files. Diffs are shown in different colors.
• the comment aligning functions in most programming major modes. M-;
• the way the tab key works. In text mode it aligns to the start of words in the line above, which makes colums really easy to do. In most programming modes it reindents the curent line. And it always does consistant formatting of the white space when you hit the tab key (i.e. it converts as many spaces at the begining to tabs as possible and fills the rest with space characters.
• You can convert all tabs to spaces if you want

And various other wonderful things too numerous to mention here.

Nuance