Who is more powerful, Angad or Ravana? Who will win, Angad or Ravana?

 Angad would crush Ravana like a bug in physical combat. Angad is the strongest and most agile Vanara in physical combat besides Sugriva and Hanuman.

• Ravana and all the demons together were incapable of moving Angad,’ s leg from the ground.
• As per Ramcharitmanas Angad already defeated Ravana in close combat. He tied Ravana with his tail and kicked him so hard that Ravana became unconscious.
• Angada made Kumbhkarana unconscious with a single slap who was physically superior to Ravana.
• Vanaras were powerful because of Brahma,’ s boons to vanaras. Brahma created vanaras to be more powerful than devas. They were capable of hurling mountain peaks, using rocks and stones as their weapons and could fly in the sky.

In a hand to hand combat Angad would have effortlessly defeated Ravana.

In a full fledged battle Ravana would have effortlessly defeated Angada had he used weapons and fought with full strength.

Ravana was quite skilled and had showed extraordinary feats in battle. Ravana hurled showers of mountains on Rama using his maya and many invincible and infalliable weapons. Ravana had advantage in creating illusions and infalliable weapons.

Ravana defeated Sugriva by striking him with a single arrow who was physically superior to Angada as Sugriva was able to kill Kumbha son of Kumbhkarana who had defeated Angad.

The enraged Ravana, taking that arrow with the speed of a thunder bolt of Indra the Lord of celestials and possessing the brilliance of a fire, hurled it to kill Sugreeva.

That arrow released by Ravana's arm reached Sugreeva, having a bodily splendour equal to that of Indra's thunder bolt, and pierced his body in its flight as formerly Guha's spear when he discharged it at the Krauncha Mountain.

Wounded by that arrow, which bereft him of consciousness, that warrior fell moaning to the earth. Beholding him falling on the ground, deprived of his senses in the battle-field, the demons raised a shout of triumph.

Source : Valmiki Ramayana Yuddha Kanda Sarga 59

Even when all the vanaras gathered up against Ravana he crushed the entire vanara army using deadly Tamasa missile

Angada was just physically powerful but was nothing compared to Ravana in terms of a warrior.

Why can't Ravana be able to lift the foot of Angad if he had lifted Kailash so easily?

 To tell the truth Angad's foot had more weight than the whole of Kailaash and Bhagwan Shiv, AT THE MOMENT.

Think what would have happened if Angad's foot had been uplifted. What would had happened?

As Angad was a great devotee of Sri Raam if Angad's foot had been uplifted, The name of Shri Vishnu and the trust of the name would have been considered false. As Raam ji's name can never be false and Moksha giving as true as death, no one in the court of Raavan was able to lift Angad's foot. It wasn't just the weight of the foot it had the weight of all existence. No one can except Sri Raam himself can uplift the weight of the Brahmaanda itself.

As Raavan was a param devotee of Bhagwan Vishnu in reality if he would have uplifted Angad's foot it would have meant that Shri Ram's name is false.

And, if Raavan would have not uplifted it it would have been a black mark on devotion. It would have been an insult to Prabhu Bhakti, the basis of God and his devotees himself, the basis of the universe. Thus, Sri Raam didn't made Raavan even try to uplift Angad's foot. Angad himself retreated his foot and asked him to touch Sri Raam's foot not his.