I have a love/hate relationship with NGC3918 (Blue Planetary). It's a beauty to find but
finding it is always the problem I have
I am constantly forgetting the star hop then having to re-learn it all over again!
The two that stand out in my mind as objects that absolutely gob smacked me would have to be Tarantula Nebula and first viewing of the Orion Nebula. Holy moly
I was so lucky to have pristine, very dark skies for my first viewing of both and borrowing some better eyepieces so I was just absolutely speechless!