That would be an interesting fight.
And I agree, Shino is probably stronger. He´s not as smart as Shikamaru but he´s definately up there and his combat tactics, in my opinion, surpass the ones Shikamaru possesses.
Shino doesn´t need other ninjas to help him at most times since he has the bugs.
Shikamaru trully shines whenever other ninjas are around him to follow his lead, so 1v1 against Shino would mean defeat, or rather, he would just quit.