I've always been something of an achievement junkie, but there are a few that I am exceptionally proud of. It seems silly, but the reputation achievements are often my favorites. The Diplomat was particularly frustrating, seeing as how I was experiencing constant lag throughout the entire grind with the Timbermaw and the Kurenai. The frustration, however, simply made that achievement something I am proud to brag about to this day -- and my warlock loves showing her title off to anyone who deigns to pay attention.
Of course, she does have ways of making people pay attention ... ah, but I digress!
Whether you tirelessly slaved away, grinding reputation for an obscure faction (or several of them); collected pet after pet in the hopes of obtaining Lil' Game Hunter; or worked endlessly to down the Lich King for the coveted Bane of the Fallen King, I want to hear about it your proudest achievement moment in WoW. It can be anything, from the random or trivial to something you actually had to put a lot of effort into to obtain.
So, fellow WoW friends -- which achievement are you most proud of?