Ooo, are we talking about favorite episodes? Most of mine utilize the entire cast of mane characters. "Dragonshy", "Sonic Rainboom", "The Cutie Mark Chronicles", "Bridle Gossip", "Swarm of the Century", "The Ticket Master" and even episodes 1 and 2 because I feel they get better when you're familiar with the characters.
Worst episode? In my opinion, probably "Over a Barrel". Serious lack of Big Mac, RBD's quick and total turn around of her stance on the situation (it just didn't seem consistent and actually confused me at first), and Pinkie's below average song (though it's now quite funny how bad it is). With that being said, I still enjoyed the episode. I just think it's at the bottom of the barrel. The comedy was great just like in "Feeling Pinkie Keen" but the general execution was just okay.
I like "Griffon the Brush Off" because of how Gilda gets what she deserves and how she brought it on herself. I really wanted Pinkie to get in Gilda's face after she made Fluttershy cry. Actually, I wanted Pinkie to rip Gilda's face clean off but I knew that wasn't going to happen.