Total ODIs played by Tendulkar: 463
Tendulkar's ODI average: 44.83
Tendulkar's total ODI runs: 18,426
Total ODIs played by Sangakara: 404
Sangakara's ODI average: 41.98
Sangakara's total ODI runs: 14,234
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Total Tests played by Tendulkar: 200
Tendulkar's Test average: 53.78
Tendulkar's total ODI runs: 15,921
Total Tests played by Sangakara: 134
Sangakara's total ODI runs: 12,400
Sangakara's Test average: 57.40
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From the above stats, we can conclude that Sangakara was a better overall contributor than Tendulkar. Test is superior to ODI and hence Test performance should carry more weight.
We also have to remember Sangakara had the additional burden of keeping (in ODI particularly).
So, Sangakara was better.
@Buffet