If Spain got Fez (extremely unlikely, but hypothetically), I'd imagine the Rif War might go more in the Riffians' favour. Although on paper Spain would control much more territory, its presence in North Africa was always more tenuous than France's, and now it'd have to assert effective control over much more of North Africa -- including Morocco's second-largest city, former capital, and religious capital (whose madrassahs and mosques were deeply tied to independent-minded zawiyahs, ribats, and marabout orders throughout North Africa).