Aoi
Terrarian
Definitely The Destroyer, the probes kill you so fast, and getting trapped by the destroyer almost always causes death. Twins is the easiest by far because of the nerf, just create a sky bridge and add fire places and heart lanterns then take your Spectre Boots and run like hell while firing backwards, if you're melee it's hard, but if that's the case then just just wait until you get the True Nights Edge. Skeletron prime is harder than the twins but as long as you learn his patterns and dodge well enough you can defeat him just as easily. Overall, in my opinion, Twins is the easiest then Skeletron then The Destroyer.