My opinion of Aisha is the opinion of the Qu'ran. Read Surat al Tahrim Verse 1-5. It is a scathing attack on Aisha and Hafsa, which is not disagreed upon even by salafi scholars like Ibn Kathir.
This section describes a story when the prophet told his wife something, which she told the other wife, and the prophet found out, when she asked how he said 'allah almighty told me'.
This actual event was when he told Aisha that he is going to another of his wives, Zainab ibn Jahsh, and that she has very nice honey that he drinks. She , Aisha, told Hafsa (another wife and daughter of umar) that this is where he was going and they became jealous. They conspired to stop him going, by telling him his breath smells. When he returned this is what they told him, and he said 'i will not eat anymore', and later he found out about this conspiracy against him. These verse later came. In verse 5, at the conclusion of the story, it says
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Perhaps his Lord, if he divorced you [all], would substitute for him wives better than you - submitting [to Allah ], believing, devoutly obedient, repentant, worshipping, and traveling - [ones] previously married and virgins.'This is undoubtedly talking about Aisha and Hafsa, there is no disagreement behind Sunnis and Shias. How do you expect me to love someone that the Quran condemns!!!! subhanallah.
Another reason was her fierce hatred of ahlul bayt. She started a civil war against Ali 25 years after the prophets death. She could not stand to see him in power. She wanted to kill him. In the battle of Basra, she marched with 13,000 soldiers into Ali's army, and hamdullilah she lost. Her own brother, Mohamed Ibn Abi Bakr, who we the shia love, fought against her!. If you fight a rightly guided caliph, what do they make you? that is the question I pose to my sunni brothers.