The long name, of course.

Now whatever you do, long names should be reserved to infrequently used things. If a long name litters your program, you'd better use a shorter one. Conversely, short names belong to frequently used things. This is because a long name is a cognitive burden. On the other hand, one needs to learn what is behind each label, and don't want to forget it.

Fortunately, good long names (such as "PatagonianSeaLion") tend to be about very specific things. So specific that you rarely need them. But there can be bad long names, like "System_Out_Println". Something this pervasive should never have such a long name.