“sledging” has been in the news here because the Australian and English cricket teams have been engaging in a lot of verbal back-and-forth during The Ashes (even getting American attention!).
The short-a is a harsh sound to me. For example, my least favorite of all normal women’s name is Pam (nothing personal against the many great Pams I’ve known). I usually don’t like short-a words, but with “trash” it makes a fair bit of sense given what the word means. For this reason I would probably pick trash over rubbish in a head-to-head, but would take rubbish over garbage.
On the other hand, sledging to me connotes an image of dogs transporting something across the tundra.
Jeremy’s winner: trash-talking (easy)