It's hard to compare them with Allegri because Allegri had Ibra's Milan and this Juve. What have those 2 ever had?
Sarri has had Empoli and Napoli. Has he outperformed their talent level? I would say yes.
Spalletti has had Roma a couple times now and has never won the scudetto but I always thought they were better than the sum of their parts. And I like how Spalletti can change formations to accommodate his players.
For me, I would *cautiously* rate them both. People can make fun of Spalletti's 7-1 to Man U, they can say he is not solid defensively but what if you give him all our CBs and suddenly he's a good defensive coach? It's impossible to know.
I would skip all the unknown and go straight for Simeone