I have Holmes at 3 myself. It’s all opinion. Once you factor in - H2h it really becomes subjective. 4-8 imo is a fair ranking of Lewis.
Lennox Lewis a true all-time top heavy. Part of this is due to his physique, but nonetheless he is a great. Weaknesses when compared to others? Possibly just stamina (when compared to other 200lb+ guys)... could he do 15? 20 rounds and beyond? (if required) And durability. Could he take the punches that Ali or Holmes took and come back to win? Doubt it. But he had so many other qualities.
He is the most complete HW boxer I have seen in the past 30 years. His weaknesses were clear in his losses to McCall and Rahman, the narrow win over Mercer and the close barnstormer against Vitali. When he abandoned the jab and long game. When he was caught on the inside losing concentration. Or working at mid range and inside he was vulernable to being outworked and countered. Steward made him close to unbeatable for a period of time, and the only thing that could beat him was complacency. Mercer nearly outworked him, but that was prior to the Steward makeover of his style. McCall and Rahman caught him on the inside losing concentration. Vitali and him were in an all out war which was undoubtedly when he was already past his best, and he wisely avoided the rematch.
Hard to judge Lewis, he reached his prime and his best when his closest competitors like Holyfield, Tyson were past it. But to Lewis's credit, he would be very good at adapting to his opponents style and match up