Don't start this here bro. To each his own caliph. Whether you accept Umar as the caliph or whether you believe Ali was the rightful heir to the caliphate, you are entitled to your own opinion. Pulling out history books and trying to justify one over the other is only going to worsen the sectarian conflict that has plagued the Muslim ummah for more than 14 centuries.
I seriously believe we need to bury this topic. The caliphate is not a feasible solution given the divide in modern day Islamic sects. I don't want to use Christianity as an example but I'm compelled to. Although divides between the various Christian sects such as the Protestants, the Catholic, the Presbyterian and the Orthodox are set in stone, the leadership Christian countries are driven by commercial interests and national identity alone. Although state leaders may choose one sect over the other in the practice of their rituals, the influence of religion is confined to their private lives. It wasn't always like this. At one point (as is the case with Islam now) religion ran the marketplace. There was unrest, suppression of science and great loss of life, but with time (and tragedy) they were taught the importance of the separation of religion from the functions of the state.
If you want to watch Pakistan flourish you will need to put Pakistan (and the Islamic democracy it stands for) before the operation of religion. Before I'm pounced on for being a heretic (There isn't only one Hakimullah Mehsud in this country, its flooded with them) here is some food-for-thought.
The Quaid's 3-word edifice upon which this nation stands reads Faith, Unity and Discipline. Therein lies a grave problem. Because although Unity connotes the aspects of unanimity and inclusiveness, Faith connotes belief alone. The problem with connoting belief alone is that different sects of Islam have different sets of beliefs. Faith for the Ahmadis is exclusive of the set of principles that guide the Shias and the Sunnis and there teachings separate from those that inspire the Bohris and the Barelvis. Hence Faith is Multiplicity; and Unity is Singularity and both of these are at loggerheads. Plurality brings colour to national life but forming a nation on the plurality of faith before establishing the concept of national unity and identity is an unfortunately shortsighted attempt to invoke national harmony. This is without doubt a good basis for a thought-provoking research paper which I intend to pursue sometime later this year but I seriously do hope my ramblings here are coherent enough for comprehension.
Like I said earlier, to each his own take on Islam. As Pakistanis in dire of need of direction we need to put Pakistan before the teachings of faith. Take this lunatic up there for example. He's put his faith before Pakistan and lo and behold - 40,000 Pakistanis dead.