Whereas I have always used `w` and did not even know that `e` existed (not that I can see an obvious advantage to it). Ahh, vim.
Most of the time it doesn't really matter. But if you know you want to append to a word you can hit that target immediately by using `e` (`ea`). Or if you want to prepend, you can use `wi`.
Note that `i` and `a` have a similar pairing to `w` and `e`.
Precision. I use e/E more often than w/W when editing a line or creating macros, but w/W for moving around. But more often i search with f and jump to next match with ; if I didn't hit the target right away. / then n if I'm moving to another line.