One of the many allegations against Muawiyah, (and Uthman also) is that he was an Umayyad and that was a clan which the Prophet (s) hated and that it always disliked Islam.
The fact is that when Islam arrived, people from different clans embraced Islam or opposed Islam and there was not a clash between tribes but there was a clash between groups having different beliefs, the Muslims and non Muslims, and both these groups consisted of Hashimites and Umayyads along with people from other clans. Many Umayyads embraced and supported Islam, and many Hashimites opposed Islam. This is a historical fact. Abu Lahab and Abu Jahal were Hashimites, who doesn’t know their anti Islamic activities? Abul Aas ibn Rabiah and Uthman ibn Affan were Umayyads. (Though Abul Aas hadn’t embraced Islam in the beginning, but he helped the Muslims from the beginning, especially when the Muslims were expelled from their homes as a result of social boycott, he would bring food to them). Similarly, Uthman also supported Islam in various ways, on the occasion of battle of Tabuk, he brought so much wealth to the Muslim army that the Prophet (s) said:
ما ضر عثمان بن عفان ما عمل بعد هذا اليوم
Nothing can harm Uthman ibn Affan after this day
The Prophet (s) not only married an Umayyad himself, but he married three of his four daughters to Umayyads, and only this is enough to destroy the myths that he hated the Umayyads. But this is not the end, we come to know that:
1. Hussain’s daughter Sakina was married to an Umayyad, Zaid ibn Umru ibn Uthman, the grandson of the third Caliph 
2. Hasan’s grand daughter, Umm Qasim bint Hasan bin Hasan, was married to an Umayyad, Marwan ibn Abaan ibn Uthman, the grandson of Uthman, the third Caliph. 
3. Jafar ibn Tayyar’s grand daughter, Umm Kulthum was married to Abaan, son of Uthman. 
4. Abbas’s grand daughter, Lubaba bint Ubaidullah was married to Walid ibn Utbah, the grand son of Abu Sufyan. Abbas and Abu Sufyan were close friends from the beginning. 
5. Hasan’s grand daughter, Nafisa bint Zaid , was married to Marwan bin Hakm’s grandson Walid bin Abdul Mulk. 
6. Ali’s daughter, Ramla, was married to Marwan’s son, Muawiyah 
7. Hasan’s grand daughter, Khadijah bint Hussain, was married to Harith bin Hakam’s grandson , Ismail bin Abdul Mulk. Harith was the brother of Marwan bin Hakam. 
8. Ali married an Umayyad, Umamah, daughter of Abul Aas ibn Rabiah. 
 Tabaqat ibn Saad Vol. 1, p. 247
 Jumhuratul Ansab, Vol. 1, p. 85
 Muarif, by Ibn Qutaiba, p. 90
 Muhabbar, p. 441
 Tabaqat ibn Saad, Vol. 5, p. 234
 Nasb Quraish, p. 45
 Nasb Quraish, p. 52
 Sulaym ibn Qais, p. 226
Aside from these relationships, the Prophet (s) also gave high ranks to the Umayyads in his life.
1. Utaab ibn Usaid Umwi was appointed the governor of Mecca after Mecca was conquered
2. Khalid bin Saeed Umwi was appointed the Aamil on Yemen.
3. Abaan bin Saeed Umwi was appointed the Aamil on Bahrain. 
4. Uthman ibn Abil Aas was appointed the Aamil on Taif. 
5. Abu Sufyan was appointed the Aamil and Amir on Najran. 
6. Muawiyah was appointed the scribe of the revelation. 
7. Yazid ibn Abi Sufyan was made the Amir of Tayma.
8. Uthman was sent as ambassador by the Prophet (s) and when there came reports that he has been killed, he took bayah from more than a thousand companions to take the revenge.
 Minhaj us Sunnah, Vol. 3, p. 175
 Tahdeeb al Tahdheeb, Vol. 5, p. 491
 Sunan Darqutni, Vol. 4, p. 16
 Tarikh Islam, by Imam Dhahabi, Vol. 2, p. 309
 Muhabbar, p. 126
Furthermore , we read that
1. When Muhammad ibn Hanafiyah died in 81 H. , Abaan ibn Uthman lead his funeral prayer. 
2. When Abdullah ibn Jafar died in 80 H. , Abaan ibn Uthman lead his funeral prayer. 
3. When Hasan died in 50 H. , Saeed ibn Aas lead his funeral prayer. 
4. When Abbas died in 32 H. , Uthman ibn Affan lead his funeral prayer. 
 Tabqat ibn Sad, Vol. 5, p. 86
 Nasb Quraish , p. 86
 Sharah Nahjul Balagha, ibn hadeed, Vol. 4, p. 25
 Istiab, Vol. 3, p. 100
That is why Ibn Qayim said:
ومن ذلك : الأحاديث في ذم معاويه . وكل حديث في ذم معاويه كذب وكل حديث في ذم عمرو بن العاص فهو كذب وكل حديث في ذم بني أميه فهو كذب
And amongst these (fabricated) ahadith are those in the criticism of Muawiyah, and all the ahadith in his criticism are lies, and all the ahadith in the criticism of Umru ibn Aas are lies, and all the ahadith in the criticism of Bani Umayyah are lies.
Al manar al Muneef , p. 110
Similarly Mulla Ali Qari says in his book , Mawdu’at
ومن ذلك : الأحاديث في ذم معاويه … و ذم بني أميه
And amongst these (fabricated) ahadith are those in the criticism of Muawiyah, and in the criticism of Bani Umayyah.
Mawdu’at , p. 106
Actually when the Abbasids snatched power from the Umayyads, they did a huge propaganda against the Umayyads so as to give a reason for their revolt.
The purpose of this article is not to show that there were no black sheeps in the Umayyads, but to show that the Umayyad clan as a whole had both good and bad people just like the other clans.