Which basic drug will have a faster onset of action: one in which the pKa is < pH, or one in which the pKa is > pH?
the drug with a pKa < pH will have a faster onset of action
For a basic drug, the active form is the nonprotonated nonionized form (remember B + H+ ↔ BH+). So, the onset of action is faster if the equation is driven toward the nonprotonated nonionized side (which occurs when the pH is high, aka less [H+]).
See example from the notes of Alfentanil having a pKa of 6.5 in a physiologic pH of 7.4. Alfentanil had a faster onset of action than Fentanyl, which had a pKa of 8.4.