Sachin Tendulkar is the slightly better Test batsman. Tendulkar has achieved more in his career than Ponting and he owes a sharp decline combined with prolonged tennis elbow to his unflattering career statistics. Looking at the LG ICC rankings
comparison, it would seem that Ricky Ponting is the more consistent performer, on a constant rise. However, a closer look would show that Ricky Ponting was not a great batsman in the early years of his career, whereas Tendulkar took off quite quickly, despite is early debut.
Ricky Ponting was not fantastic in the 1990s. The 1990s was the final period before a mass flattening out of pitches around the 2001/2 era. It also coincided with the greatest era of fast bowlers, imo. Waqar, Wasim, Pollock, Donald, Gough, Mcgrath...the list goes on. Whereas Tendulkar succeeded in scaling the heights in the toughest of periods, Ricky Ponting sunk into mediocraty.
However, on the other hand, Tendulkar failed to cash in when the standard of bowlers fell and the pitches flattened in the 2000s. This was a decline of epic proportions combined with tennis elbow injuries - as mentioned earlier. I cannot fully explain, nor condone Tendulkar's drop in form. Tendulkar has played longer than Ponting and amassed 11782 Test runs compared to Ricky Ponting's 9776 - I believe that having played more Tests, a decline of sorts which has been absent in Ponting's career can be explained by assuming that one will consume Ponting, later in his career too. Even if it doesn't, I still feel that Tendulkar's success at a higher level for an entire decade exceeds Ponting's slightly greater domination at a lower level for a similar amount of time.
The age old arguement is also that Ponting is home in Australia and so is better than Tendulkar who bats on the 'paata' tracks of India. However, Ponting has shown himself distinctly useless in India; with 172 runs at 12.28, compared to Tendulkar's 5096 at 54.95. Conversely, both have succeeded in Australia, proving that Australia is ideal for both batsman - this could partially explain Ponting's superior statistics too; Tendulkar with 1522 runs at 58.33 and Ponting with 5891 at 62.67.
I could bore you with saying that Ponting has had a better line up and Tendulkar has had pressure, etc...but I don't think that it is necessary to outline such well known intangibles.