Some of the best episodes of Lost include 'Pilot,' which introduces the main characters and sets up the intriguing premise of survivors on a mysterious island. 'Walkabout' is another standout episode that delves into John Locke's backstory and reveals the island's potential for miracles. 'The Constant' is often praised for its emotional depth and complex storytelling, involving time travel and Desmond's love for Penny.

'The Constant' is widely regarded as one of the most emotional episodes of Lost. It focuses on Desmond Hume and his love for Penny Widmore, featuring a heartfelt phone call that transcends time and space. The episode's unique narrative structure and emotional weight make it a fan favorite.

'Through the Looking Glass' is often considered one of the most mysterious episodes of Lost. It serves as the Season 3 finale and features a dramatic showdown between the survivors and the Others. The episode is known for its shocking flash-forward twist, which adds a new layer of mystery to the series.