My favorite Volume would definately be 26. So much happens.
-SpecialShipping hints(yaaaay)
-Silver accepts that his father is Giovanni
-Giovanni saves his son from the harm of fire
-Silver ditches that funky Team Rocket attire. O.o
-Giovanni remembers when Silver was young. This part just struck me at the heart. It was very moving.
-Red, Yellow, Blue, Green, and Silver are turned to stone, which depresses me, but gives me a heroic view of them.
And 22 is good. The lost one, you know? We see how Silver and Blue escaped from Mask of Ice. Plus, there's ChosenShipping hints...I just like shippy moments...and I don't really support the ship.
My least favorite...I really dunno. :/ I like all of them...