My prefix a conjunction is,
an alternative thing.
My infix, add an l to it,
there's royalty, and king.
My suffix negative it is, can't add another hint.
But all the words together fit
and I'm a spice, like mint.
The answer is.... (drumroll)
Or is a this OR that choice conjuction
Rega with an l is regal or seeming like royalty
No is a rejection and considered "negative"
Oregano is a type of herb