when it comes to Bach I am surprised more people don't mention pieces like this

https://www.youtube.com/watch?v=tsxP-YjDWlQ (arioso from the cantata 156, here for oboe)

which I think stands up just fine against pretty much any other classical piece baroque or not.

Personally I have a very big soft spot for his organ works, as I play (badly) some organ myself, and among those I don't see the trio sonatas recommended nearly often enough (here is a live recital of all of them, which is super impressive)

https://www.youtube.com/watch?v=eK9irE8LMAU

among those I probably enjoy the most the vivace of BWV 530. Other favorite pieces are the passacaglia and fugue https://www.youtube.com/watch?v=nVoFLM_BDgs the toccata adagio and fugue in C major https://www.youtube.com/watch?v=Klh9GiWMc9U (the adagio especially is super nice), but there's so many. Among organists I often come back to Helmut Walcha, and am always amazed at how he was able to learn everything just by listening, him being blind.

If you're going to give them the triosonatas, you gotta give them the good one: https://www.youtube.com/watch?v=EOTtDYTc5JY&list=PLCDB42413B...

Put on a good set of headphones and go sit in the corner.

Also obligatory: https://www.youtube.com/watch?v=Ah392lnFHxM&list=RDAh392lnFH...

The thing I appericiate most about bach is:

you can play it fast.

you can play it slow.

you can play it with an ensemble of random instruments.

you can play a single voicing all by itself.

all of it screams "musical". which, if you do play say, Tuba, or one of the larger instruments, is a godsend, as most of your lines in other pieces will bore you to death.