How to extract subsets in a list based on the largest element in the subset?

First@MaximalBy[#, Last] & /@ example

{{a, b, 3}, {e, f, 8}, {a, b, 4}, {e, f, 4}}

Map[Last @* SortBy[Last]] @ example

 {{a, b, 3}, {e, f, 8}, {a, b, 4}, {e, f, 4}}

Also

#[[First @ Ordering[Last /@ #, -1]]] & /@ example

{{a, b, 3}, {e, f, 8}, {a, b, 4}, {e, f, 4}}