Which commentator of the Brahma Sutras followed Badarayana (Vedavyasa), the author of the Brahma Sutras, most closely?
Ramanujacharya's Sri Bhashya is the closest to Vyasa's views because it follows Bodhayana's Vritti. Bodhayana was a student of Vyasa, and he wrote a commentary on his guru's sutras. So, naturally the commentary that follows Bodhayana's commentary will be the most accurate to Vyasa's teachings.
We can see this from the introduction of Ramanujacharya's and Shankaracharya's commentaries on the Brahma Sutras.
Bhagavad BodhAyanakrtAm vistIrNAm brahmasUtravrittim pUrvAchAryAsamchikshipuh |
TanmatAnusAreNa sUtrAksharANi vyAkhyAsyante
The lengthy explanation (vritti) of the Brahma-sûtras which was composed by the Reverend Bodhâyana has been abridged by former teachers; according to their views [and his] the words of the Sûtras will be explained in this present work.
Whereas Shankaracharya says:
YathA ca ayamartho vedAntAnAm tathA vayam asyAm shArIrakamImAmsAyAm pradarshayishyAmah |
That all the Vedânta-texts have the mentioned purport we shall show in this so-called Sârîraka-mîmâmsâ.
As you can see, Ramanujacharya is writing his commentary fully based on Bodhayana's Vritti, as well as former Vedantic philosophers such as Tanka, Dramida, Guhadeva, Kapardi, and Bharuchi, whereas Shankaracharya does not.
Here are the main differences between these two introductory sentences:
- Usage of passive voice giving importance to the subject being propounded rather than the person doing the propounding
- Quotes the previous acharyas and mentions that the path shown by them is being followed
- The tone and tenor of the sentence is of modesty and sincerity
- Short, crisp, and pithy introduction
- Usage of active voice giving importance to the person rather than the subject
- Here too, usage of plural while referring to his own self
- No reference to the previous acharyas or mention of that path shown by them is being followed
- The tone and tenor of the sentence is of a sort of pride and self-esteem
Now the reason why Shankaracharya was using that tone is because he was debating Buddhists, and so he had to prove his arguments to them. Because Buddhists don't accept the Vedas, he had to prove his points through pure logic and not scripture. Hence his writing style.
From this we can see that Ramanujacharya's commentary is the closest to Vyasa's views.
Shankaracharya does cite and agree with the ancient commentator Upavarsha, but he also disagrees with "other" ancient commentators. Advaitin scholars after his time say the "other" he disagreed with is Bodhayana. Some people think Bodhayana is the same as Upavarsha, while others think he is different.
If he is a different person, he came after Bodhayana and was probably a sishya of him anyways since Upavarsha abridged Bodhayana's Vritti:
A Purva Mimamsa work called the "Prapancha Hridayam" says,
...On this Mimamsa Shastra of 20 chapters, Bodhayana wrote a Bhashya that bore the name Krtakoti. Fearing that the great length of this commentary would cast it into oblivion, Upavarsha somewhat abridged it...