I think Meld just wins for me too. Riddles has lots of great, touching character moments, but Tim Russ showed just how versatile he could be in Meld, I thought.
Other episodes I think deserving an honourable mention would be Learning Curve and Alter Ego and Flashback.
Tuvok is my favourite Voyager character and it's a damn shame he didn't get utilised more. Another thing to add to the list of Voyager's "If only" moments