It's sounds daft, but I haven't been that bothered about any of the trophies we have won, since they have tended to be won against a backdrop of mediocrity and/or failure.
For example, winning the Europa League means you have failed to qualify for the knockout stages of the CL (or the competition altogether) and LvG was sacked about a week after we won the FA Cup. I was at the League Cup final when we beat Southampton, and it was a good day out, but again, we were outplayed at times and it just felt a bit hollow, getting overly excited about scraping past a mid-table team in a League Cup final.
I did enjoy that period of games under LvG when we beat City, Tottenham and Liverpool (i think) comprehensively in the space of about three weeks. It wasn't just that we won those games, it was the way we won them. Say what you want about LvG, but I have never before seen United so dominant in games against Liverpool and City as we did at times under him. Even under SAF, those games tended to be frantic. helter-skelter, edge-of-your-seat type encounters.
Also, and I have been critical of Ole lately, but I have enjoyed his management of the club, for the most part, over the last two years. I think fans are very quick to forget how bad we were. Under Moyes, LvG and Jose, that run we just endured was common. That's the first time really we have been embarrassed under Ole. Under Moyes, LvG and Jose, I feared every single game, I could never see us winning, especially if we went a goal down. Under LvG, if we conceded first, it felt like you might as well get up and leave.
So I'll also include Ole's 2-0 victory over City just before lockdown, and the 2-0 away win at the Etihad, because it felt like there was no fluke to either victory and we had started to build a squad genuinely capable of challenging again.