That's tough. I want to instinctively say "lotto"...
Here's what it depends on, to me.
How much of a difference will it make to Kevin Durant if Boston is swept in the first round, makes it to round 2, or makes it to the ECF?
I get that a trip to ECF means a possible trip to the Finals, but I'm assuming you are saying ECF would be the last stop.
Regardless, my guess is winning the lotto is better for Boston. We either keep Ben Simmons, or have a god-tier asset to lure a sidekick for Durant with.