the most attractive locomotive livery?

For an attractive livery, it would be hard to go past this charcoal and dark red scheme that the DSB or Danish State Railways chose for its locomotives some three decades ago (since replaced with a midnight blue with emblems scheme).  And in the case of the EA class, the fluting along the sides adds to the appeal.

This shows two of the 22 electric locomotives delivered between 1984 and 1992 for DSB's mainline electrification project in 25 kV AC.  They are Bo-Bo type with a 4000 kW output.