For me it depends on if you mean “could only have one headphone that had to cover as many bases as possible” or “can have other headphones, but only one of the two Vérité open/closed options”.
If it’s the former, then the Vérité Closed would likely be my choice - since I do need isolation from time to time. If it’s the latter then the Vérité (open) would be how I’d go.
The Vérité open and closed sound far more alike than they do different. The closed has a bit more tonal weight and a bit more sub-bass energy (depending on pads), which results in a slightly warmer overall sound and a bit more perceived punch, but doesn’t sound “closed” at all, and actually seems to present a more vividly dimensional, and expansive, stage.
Now, Vérité Closed vs. Stellia is going to take more listening to finalize a decision on, and may simply come down to which pads are on the Vérité - but what I can say already is that those are the two headphones in contention for my personal choice for “best closed back headphone, period”.
I posted a frequency response comparison between these two here.