You can't really pose that question without fleshing it out with the cup/league performances for each scenario though.
If you said whilst finishing 2nd in the League we would be knocked out of every cup competition at the first hurdle, then maybe it becomes a difficult hypothetical. But then what is the League performance whilst winning these 12 cups? Finishing 17th every year? Then no, it's not worth 80% of the games you watch your team in being a dismal experience.
Plus, over an extended period of time, you also have to apply some basic logic. If a side is good enough to be finishing 2nd in the league consistently, then the chances that they will win a cup is increased. Meanwhile, if the side is so poor they can only just about avoid relegation, then they aren't going to be much of a threat in the cups.
This season is an absolute freak, only enabled by the fact that Europa has a pretty easy format for getting to the knockouts, and has seen a very favourable run to the Semis, largely due to the lack of CL dropouts in this new format.
We won't have that luxury next season, because we either won't be in Europe at all, or because we'll be playing CL calibre teams in the actual CL.
Winning the Europa would in no way excuse this season's League performance, or justify it. We should have been able to negotiate our way to the latter stages whilst also being able to at the very least be in the top half in the League.