Of the three - Luca James Dyson for me. Archie is a bit too trendy, although Luca is perhaps slightly exotic sounding compared to Imogen (Luke or Lucas feel more a similar style imo)
Imogen is quite classic and also Celtic origin so if you want other suggestions, maybe Owen, Evan or Rhys? (Owen is my fave). It's also Shakespearean, so there's also the many commonplace "English" boys names also used by Shakespeare - Hugh, Henry, Arthur, Thomas, Toby, William, Edward, Edmund, Adam, Peter, Robert, Michael, Nathaniel, Charles, Alexander, Frederick, Nicholas, John, Christopher, Marcus, Francis, Laurence, Matthew....