Dr. Israr Ahmed is the best scholar I have come across.
Tanzeem-e-Islami, his organization, striving to establish an Islamic system of government in Pakistan:
Many of his lectures can be found at:
Another organisation, Qur'an Academy, that he runs:
Since he's based in Pakistan, most of his lectures are in Urdu. However, he does have various English lectures as well, which can be found at the aforementioned links.