Well, my favorite episode is when Neji fights the spider guy.. and I forgot the episode... 'twas around 110-120 I believe.
One of my favorites aswell...
Actually I can list my favorites that come to mind:
(EXTREME SPOILERS)
ALL the individual fights against the sound guys
Gaara vs Lee in the exams
Lee vs kidoumaro
The episode where Gaara, Temari and Gaara help against the sound guys
3rd hokage vs Oro
When the three sannins summon their respective creatures
first and second episode...we see iruka's badass side
Sasuke vs naruto
Itachi owning everyone
Itachi owning Sasuke
all that comes to mind right now...