I am a Rubyist that is just starting to dabble in Smalltalk and am trying to chose an implementation to experiment with. It seems like Squeak or Pharo would be a good choice, bu
Although not strictly a Smalltalk implementation one should not overlook Newspeak. Not as yet a production environment, but if you have been torn between Alan Kay and Nicolas Wirth as language experts Newspeak is like Smalltalk and Modula2 combined.