Holding unsuited A-K is better than holding just one of the two because you’ll get your money back by pairing the King or the Ace more often. Yes, you can’t hit the royal, but drawing 4 cards to the royal is a huge long shot anyway.
If you’d like to see the exact numbers, assuming a $1 game where you’ve bet $5:
AK unsuited is worth about $2.39.
An Ace alone is worth $2.32.
A King alone is worth $2.30.