I've been reading WW II books since forever. Italy was basically a gift to Hitler -- it's a country made for defense. But I'm not sure the Balkans, like Churchill wanted, would have been any better. And Stalin would have been very unhappy about it.
Also, the 15th Air Force operating from Italy brought lots of Eastern Europe in range of bombers.
The Italian campaign was a meat grinder.
The Balkans would have been hard to get at without having Italy in hand. Where would one have attacked, when the British couldn't take and hold the Dodecanese?
[1] But there's so few of them and the chokepoints so obvious that it's relatively easy to defend them.
If Spain had been in the war that would have been the obvious choice, but they were "neutral."