Hands down the most soul tugging moment was season 3's last episode: Abyssinia, Henry. Henry gets discharged...the good-bye scenes are hilarious.
When Radar comes into the یا and announces that Henry's plane was shot down...it was so raw and real. I still cry every single time I see it!
I've read different accounts of that episode and I'm not sure which one is true. I think the writers made the decision for that scene at the last منٹ and Gary Burghoff was دیا his lines just before the shoot. It came off as a real shock to every one.
Certainly they are all great actors, however, I am not sure if they could have pulled off the real/raw emotion of that scene had it not been a surprise. Had it been in their original script and they'd rehearsed it...well, I think it would have felt fake.
No other episode compares, in my opinion, for pulling at the دل strings and guaranteed tears.