The sort performance is always highly dependent on your data and scenario. It's hard to say one to be the worst always.
Insertion Sort [Best: O(N), Worst:O(N^2)]
Start with a sorted list of 1 element on the left, and N-1 unsorted items on the right. Take the first unsorted item (element #2) and insert it into the sorted list, moving elements as necessary. We now have a sorted list of size 2, and N -2 unsorted elements. Repeat for all elements.
Heapsort [Best/Avg/Worst: O(N lg N)]
Add all items into a heap. Pop the largest item from the heap and insert it at the end (final position). Repeat for all items.
Bubble Sort [Best: O(n), Worst:O(N^2)]
Starting on the left, compare adjacent items and keep “bubbling” the larger one to the right (it’s in its final place). Bubble sort the remaining N -1 items.
Quicksort [Best: O(N lg N), Avg: O(N lg N), Worst:O(N^2)]
