What in your own opinon do you think is the best bach composition?

his first concerto in d minor!!!!!!!!

2nd movement of Brandenburg Concerto 2.
The staggered entrance and interaction between the different instruments is really beautiful, esp. when the music moves gently into its relative minor. And i really like its simplicity( it sounds really french though, not a typically german sounding work ).

goldberg varations are very tedious, but after working for half a year, you`ll appreciate it and convince others to do the same. All the concertos--I`ve played them all, and I like the A major on the best next to the d minor.

Toccata in dm

"Adagio, ma non tanto" from Brandenburg Concerto no.6
(esp. when the bass part brings the theme)
"Der tag, der ist so freudenreich", BWV 605
"Allegro (1st mvt.) from Piano Concerto, BWV 1052
"Allegro assai" from Brandenburg Concerto no.2

2nd movement of Brandenburg Concerto 2. (since my orchestra played it so beatifully, it is also a great song)

This I agree.
The staggered entrance and the subtle change from F major to D minor is beautiful.
It`s my personal fav also. I find the interaction between the instruments is magical.