I think instead of "most missed removed card", the question should be which removed cards will you continue to use?
I was thinking along the same lines. When I play IRL games, I will either do the DXV method of just grabbing two sets and playing with those, but sometimes if there's going to be a lot of Dominion played we'll just put all the randomizers in one pile, play the first 10 cards, then next game go to the next 10 cards, and so on, sometimes playing right through the pile over the course of a weekend. (For the record, I own Base, Intrigue, Seaside, Cornucopia/Guilds, and Empires).
Woodcutter can go, I have lots of +Buy.
Thief is replaced by Bandit, so I don't need Thief.
Feast can easily go.
Adventurer I almost lean towards keeping, it's my only 6 cost card apart from Harem and Nobles. But it will probably go as well.
Chancellor I'm going to keep playing with. I don't own Dark Ages or Adventures, so I don't have Scavenger or Messenger, and I like Chancellor's ability enough that I will keep it in. It's a useful teaching tool as well.
Spy is a tough one for me. There's not a new card that replaced what Spy does, but what Spy does is kind of annoying. I know some of my opponents like playing it, but they hate playing against it. We'll play a game with a workshop or an ironworks and I'll grab 5 or 6 for my engine, and now every turn is like (I spy on you again. And again. And again. Oh wait, you're still shuffling? OK fine, but once you've drawn your hand I spy on you 6 times. Skip it, skip it, ok there's an estate, keep it there the next 3 times). Spy might have to go.
Great Hall can go, it's replaced by Mill.
Scout can go as well for Smithy Scout.
Tribute I'm on the fence with, I like the randomness in just-for-games and I like the song.
Secret Chamber can go, no one but me ever buys it because it seems too complicated. It's also kind of been replaced by Diplomat, although it's also a complicated card.
Saboteur I'm on the fence with, I never buy it but some of my opponents like it. It might stay.
For me, I'll keep using
Coppersmith for sure. In the games where it shines it's really fun, and I often try to make it work even when it's going to be hard, I don't take my IRL games very seriously. We once played a game with Ironworks and Heralds where I was able to get 6 Coppersmiths in play.