My general thoughts on Sanga is that he started off as an above average player, and perhaps went unnoticed for the first 5 years of his career. I think this is one of the reasons why he is rated a tad lower than others or as some have said, he doesn't get enough credit. Lara pretty much shattered a lot of batting records during the first 5 years of his career.
I can speak for myself and I know that I did not rate Sanga very highly maybe not until the 192 in 2007 in Australia. Even then he was for me far below the likes of Dravid or Kallis.
I have found my opinion on Sanga evolve as I have seen the player evolve. What I gathered from reading his interviews, here was a man was an excellent student of the game, always looking to improve, which is why his batting transformed so much over the course of his career. His record from 2009-2014 is phenomenal, and once he gave up keeping, he totally focused on being the best batsman that he could be.
Let's look at it this way, every time he toured England, South Africa, New Zealand in the last 5 years, he has performed well and scored at least 1 hundred, sometimes even better, this while considering the fact that he gets 2 tests in England compared to India's 4 and Australia's 5.
If he had gotten as many opportunities against these teams in the last 5 years as some of the Big 3 do, then his record would also be something like 6 centuries in 12 tests.