I lost a lot of respect for Zakir Naik when he used 'may Allah be pleased with him' to refer to Yazid, and then came on TV again to bicker with others about it and subsequently twisted ahadith out of context to try and give legitimacy to his views. As Rastafarian said, the danger is that he can very easily mislead well-meaning people. Was good to see Sunnis and Shias both calling him out on that issue.
Aamir Liaqat is a clown and a joke. If anyone takes him seriously, that's just sad. Zakir Naik is even worse and more dangerous, because he presents himself in a scholarly manner and has the power to mislead.
Note, I have absolutely no issue with scholars from all schools of thought in Islam expressing their views--and I genuinely welcome and embrace them all, whether they be the traditional tariqah-inspired Hanafi prevalent in India and Pakistan, Ithna Ashari, Deobandis, or even Wahabis for that matter. But neither Aamir Liaqat nor Zakir Naik are qualified, yet both act as if they are.
Ahmed Deedat was an excellent example of what an Allah and Rasool-loving Muslim speaker should be like.