Genoa and especially Venice are interesting candiatetes because their missions and posessions allow them to expand their foothold all across the mediterranan, as in the Balkans, Anatolia and Greece (and following Asia), Spain, the Black Sea region etc. These aren‘t nessecarily the easiest and quickest canditates (these would be Florence, Milan and Austria as mentioned) but they allow for the quickest Italian dominance over the Mediterranian, which qualifies as „best“ in my book. Note that Genua can be very hard to pull off nicely and Venice is much more consistent for expansion into Greece, the Balkans, Asia, and then later Spain and Italy.