Tarkovsky only made seven features. I've seen all seven. Solaris is the worst.
Think what you will, but I disagree. I actually love Solyaris. It's too bad you don't like it, for me, it's just a beautiful film. To be fair though, it was the first Tarkovsky film I saw, so it was an experience from that alone. I think picking a "worst" Tarkovsky film is a hard thing to do, because his "worst" is better than many filmmaker's "best." Due to this, I would never pick a worst, because there's not a film of his I can think of that I clearly like much less than the others. Andrei Rublev would be my least favorite, but that's not due to quality, I just have a hard time getting interested in the monks.
What is your favorite Tarkovsky film, Tony?
And bummer that you don't like Stalker, agrimorfee, I love that one.