I am learning the Minuet in G major, previously attributed to Johann Sebastian Bach, but probably composed by Christian Petzold.
I am learning it on a piano, but as there are other voices on my digital piano, should I switch to harpsichord or maybe some other voice to make it sound more original? My sheet tells nothing about which instrument it originally was.
I would say harpischord, since most of Bach's works preceded the piano. Not exactly preceded, but piano wasn't really famous till Bach was really old. Most of his works are being played in Organ or Harpischord when they are trying to imitate that sound.
I am not sure that trying to be totally authentic is most approriate for pieces from the Anna Magdalena Notebook, which Bach collected (some he wrote, and some he thought were worth collecting) for educational purposes, but if you do want to be authentic, I suspect that you maybe ought to play this piece and the others from the Notebook on a clavichord, as Bach seems to have believed that the clavichord was the most suitable instrument for practice purposes.
However, I sure that Bach would have been quite happy for the piece to be played on any keyboard instrument, as he seems to have been quite fond of "repurposing" some of his music for other instruments.
The common domestic keyboard instruments in Bach's time were the harpsichord and clavichord. The piano was a new invention in Bach's lifetime, but (1) he wasn't very impressed by the ones that he tried, and (2) early pianos sound very different from modern ones anyway.
The harpsichord was usually preferred for absolute beginners, since it encouraged developing clean finger-work, and it's technically much easier to get a "good tone" from a harpsichord than a clavichord. Unlike the harpsichord, the clavichord is "touch-sensitive" like the modern piano, but it needs much better finger-control than a modern piano to play it well.
The other important keyboard instrument of the time was the organ. In Germany the organ was exclusively a church instrument and playing dance music on it was considered inappropriate, but in England pipe organs were often used for secular music both at public concerts and in (large) homes. Handel wrote plenty of secular organ music, including some minuets - for example at about 12 minutes into
Of course if you play a digital piano with a harpsichord sound, the "feel" of the keyboard doesn't change and is very different from playing a real harpsichord - but use whatever sound you prefer.
