For me, it has to be “Old Boy” which is originally a Korean movie but the US version sucks so much that it remains incomparable. Another contender is “The Ring” again a Japanese movie (the ending differs between both versions, as the original one refers to the protagonist’s father sacrificing himself but the remake states that the cursed tape is being sent to someone else, passing the omen towards another stranger).
I watched Departed twice, not knowing it was a remake and I enjoyed it quite a bit. But after seeing Inferal Affairs I have to agree the Departed is a bit too “extra”, and the original is way more rewatchable than the remake