There is no "Muslim" leader currently. There is no Muslim country that is significantly stronger than rival Muslim countries either. Some have a bigger influence religion wise, others financially wise, others militarily wise etc.
Makkah and Madinah might be located in KSA but that does not mean that KSA is the "leader". Many see it this way but it's wrong. There is no Caliphate anymore either.
From 632 until 1517 the Caliphate was in the hands of dynasties originally from the Hijaz region in KSA (Rashidun, Umayyad, Abbasid) and from 1517 until 1924 it was in the hands of the Ottomans.
The only Muslim countries that are G-20 major economies member states are Turkey, KSA and Indonesia.
G-20 major economies - Wikipedia, the free encyclopedia
In terms of Muslim regional blocs then the GCC is the most wealthy financially speaking as the GCC has a almost 2 trillion dollar big GDP (nominal) as of 2015.
The GCC is also the richest Muslim region in terms of GDP per capita (nominal).
List of countries by GDP (nominal) per capita - Wikipedia, the free encyclopedia
Far richer than any other Muslim states.
In terms of military then I would say that the most "powerful" Muslim countries are Pakistan, Turkey, Indonesia, GCC, Egypt, Algeria, Iran etc.
Not sure if this thread is intended for trolling but I replied anyway.
P.S.: KSA and Turkey are not rivals so this comparison is pointless.