I think TTT extended is my favourite of the trilogy and probably my favourite film of all time. That said I looove all the movies and can clearly see why every one could be regarded as the best.
TTT has just soooo many awesome things all the time. Intro with Gandalf vs Balrog blew my mind in theaters (I sadly only saw FOTR on vhs at the time). Gollum introduction, looked great, sounded perfect. I think it spoiled the ''Avatar effect'' of CGI on me.
Some scenes that some ''Tolkien purists'' didn't like I tough were great. For instance the elves arriving to Helms Deep: fuckin awesome and I don't even really like the elves. I even tough Gimli as a comic relief worked but it went too far in ROTK. Last march of the ents, Gandalf releasing Theoden and later arriving with Eomer, Boromir scene and Sams speech. Just sooo many great moments.
Also Helms Deep as a whole is almost perfect, my favourite war scene of all time. Only thing I would remove is Legolas's ridicilous scateboarding.
And no way is TTT concidered best by majority.