I'm not seeing the Bender love as the Celtics don't need another below the rim big. If they go big, I'd rather they take Skal at #3 than Bender (and I thought Skal was mainly hot garbage as an over-aged frosh last year). Skal basically has the same skill-set as Bender except Skal has hops and can block/alter shots. I'm not advocating taking Skal at #3, just that I think he'd be a better fit for Boston than Bender (who strikes me as a scrawny version of Olynyk). With an NBA PED program, maybe Skal starts to fulfill on the promise he showed before being exposed as a passive floater at Kentucky. Boston desperately needs mobile, athletic bigs (I mean, Jerebko was probably their most athletic big last year which is really sad) so taking Bender doesn't change that equation.
Murray is still my choice if they stick with the #3 pick as I see him as the player with the best combination of NBA ready skills with room to improve (he was an 18 year old freshman; he reclassified to join Kentucky's 2015 incoming class). I like the Brandon Roy comps and while I wish he were a little more athletic, he has a nice mixture of skills and intangibles (carries himself like an alpha dog, competes defensively, has always shown well in international competitions, etc.). If they take Murray, they should be able to move Bradley for a nice piece.
Trading #3 would still be my preferred option though and I'll be more surprised than not if they do actually keep the pick.