Trash an Estate or Curse your opponents? Full Version
What makes an early-game trasher powerful, especially against an opponent giving out curses, is determined mainly by two things: how many cards it can trash at once, and the benefit it gives. 

Curse:


Develop
Island
Mine
Moneylender
Trade Route


Island fails to negate the VP loss when trashing a curse and gives no benefit when played. Trade Route likewise gives no benefit when played at this point other than the +Buy. Mine and Moneylender can't trash curses at all, so Witch away! And, well, we don't talk about Develop...

Trash:


Ambassador
Bishop
Chapel
Masquerade
Remake
Steward
Trading Post


Ambassador, Chapel, Remake, Steward, and Trading Post all trash multiple cards per play. Bishop gives similar trashing power in a multiplayer game. Your Witch is unlikely to be able to keep up cursing fast enough to hurt your opponents.

Depends:


Hermit
Jack of All Trades
Remodel
Salvager
Transmute
Trader


Hermit and Jack can't trash treasures, and the rest give little or no benefit when trashing a Copper. Now, of course your question specified that you have an Estate in hand. To me, playing any of these would be contingent on having that Estate.
For Remodel in particular, the relevant things to consider are:


Is there a 3 or 4 cost card that I really want?
Is there a decent 2 cost card my opponents can turn that curse into?