I will try and answer it this way based on what you wrote.
Basher - E-Revo because its 4wd and can do so much.
Racer - Slash because local tracks support it so much.
Durability - Equal. Maybe a slight advantage to the slash because its so well protected.
Speed - E-Revo by few mph
Maintenance - Slash due to less moving parts to wear out.
Cool factor - The Slash draws more crowds when I go to the races.