With the beauty contest going on in other threads, lets do the opposite. What do you think are the ugliest engines? No restrictions on type (electric, diesel, steam, etc...), and if you want to say why, feel free.
I'll start:
BQ23-7 - I dont think there's much to say, its pretty self explanatory.
and the SD60M "Triclops" - Just an odd duck. The middle window and the flat face just throw it all off. Going to 2 windows was a major improvement.