Here's my rating with some little review for every season:
Season 1: 8.5/10 (Impressive start, although the plot feels so slow)
Season 2: 9/10 (Masterpiece of storytelling)
Season 3: 10/10 (Omar Little the champions of people)
Season 4: 11/10 (is this a real life? Is this just fantasy?)
Season 5: 9.5/10 (such a perfect conclusion)
Season 1: 8.5/10 (Impressive start, although the plot feels so slow)
Season 2: 9/10 (Masterpiece of storytelling)
Season 3: 10/10 (Omar Little the champions of people)
Season 4: 11/10 (is this a real life? Is this just fantasy?)
Season 5: 9.5/10 (such a perfect conclusion)