After reading many novels I reached the conclusion that (for a male at least) the perfect novel needs 3 ingredients to satisfy the reader without boring him:

1 - STRENGTH : Constant MC drive to Increase his power/strength via cultivation or other means. The greater the obstacles he overcomes, the hardship, and the explosion of his power after he strengthened himself, the greater is the psychological reward. Examples: I Shall Seal The Heavens, Against The Gods, The Desolate Era.

2 - BEAUTY : An unending series of beauties in distress, with saving them as the main motivation to go on with the story. The MC should not be necessary a righteous person, but he should have a soft spot for damsels in distress. The beauties must not necessarily become part of the MC harem, they just need to be grateful to him. Examples: Womanizing Mage, Ancient Strengthening Technique, Battle Through the Heavens.

3 - WISDOM : The MC must outsmart his enemies. The most cunning, the better. Battle strength alone is not going to keep interest in the long run. Scheming and strategy, especially long term grand designs and political ploys, keep the story interesting. Antagonists also need to be crafty to make defeating them a rewarding experience. EXAMPLES: Legend of Ling Tian, Nirvana in Fire, Transcending the Nine Heavens.

So the formula is Xianxia/Xuanhuan + Save-The-Beauties + Cunning Protagonist.

This is a list of the best novels of this kind.