Baron or End
Why do people insist on getting Baron when there's only one enemy alive, wide open inhib, and one nexus turret standing? You have FORTY seconds to take down a single turret and kill the nexus. But instead you go for Baron and leave the two smart teammates to try to push the wave and take on a Kayle with GA.
FORTY seconds of virtually no opposition and just a single turret in the way of winning the game. And the only thing on your mind is Baron?
you may end up losing 3 people. In certain situations it'll be better to get baron so you can go in and push better.