I think overall they are pretty close. Both guys dont have that ATG in their prime on their resume but had good solid runs. I would think Larry was more capable of beating that ATG than Lewis was because he was more skilled than Lewis, but based on their accomplishments I think they are pretty close. Larry for the most part fought guys who complimented his style very well and I would say the exact same thing about Lewis and I think Larrys opponents had more overall skills than Lewis'.
I think a lot of Lennox Lewis, but I just think Larry Holmes was a more complete fighter. Hell, Holmes was a top 10ish Heavyweight into his mid 40's. He rates as an all time top 5 Heavyweight in my book.