Richter was a fine musician, but what he plays is vastly alien from the musical practices of the 18th century. In other words, he plays Bach in a heavily Romantic/20th century style which in my opinion greatly dilutes the musical quality of his performances. But you can't really compare Richter to say, Koopman, because while the latter plays Bach the way Bach would have played his own music (or at least similarly), Richter plays Romantic (not Baroque) Bach.
This is my favorite recording (Ton Koopman and the Amsterdam Baroque Orchestra):
re: That clip; actually this is one of Ricther's more "authentic" recordings (His recording of Bach's Passcaglia in c minor is completely Romantic without any semblance of Baroque style or aesthetic). I think that this particular recording can be a bit hard on the ears due to the poor quality of the harpsichord. A lot of the older 20th century harpsichords can be really tiring to listen to - either they sound like tin cans or the sound is just loud and unfeeling (it can also be that the performer is a pianist playing on the harpsichord, not a harpsichordist who has studied the unique technique required to master this instrument).
I definately have to say that I think Koopman's recording is far superior.