In my side, I could distinguish between professional and personal.
Professional, there have been very nice moments during the engagemetns, particularly when overcoming a big roadblock, etc.
For instance, I remember as very special the 1st time I was invited for a Steerco, given that I had own en-to-end the workstream we werer going to present to CEO & board. I was shaking, but felt very recognised!
However, the ones I remember most are more related to the team. Some of the best moments of my life, and craziest, I´ve lived with my former colleagues, most of them became best friends by now.
For instance, I remember one Thursday night, after a long and difficult week by the client site, that we went out for dinner to celebrate. We had tooooo many margaritas, thinking that Friday was going to be really really chilled -partners had the meeting with the clients, we would be alone in the team room, chilled day with no action points until the meeting was over-. However, the following morning, we were last minute invited to the meeting just to be able to talk about the details. It was terrible! We were totally hungovered and destroyed, not even time to wake up properly, some even without showever ,since we got called totally last minute and jumped out of bed to a taxi to the meeting.