Just finished catching up on most of these. This is how my list looks as of right now.
1. Stalker - my second fave of all time, at the moment.
2. Ivan's Childhood - Tarkovsky's most straightforward story shows that he can be a pretty good storyteller in addition to an amazing image creator.
3. Solaris - My first Tarkovsky and one I probably need to revisit. The verdant green scenery + heavy rain has really stuck in my mind as one of Tarkovsky's two major images.
4. Andrei Rublev - On the long side, but I liked the core of each section.
5. The Sacrifice - Probably too heady for me, though I liked the Bergman actors showing off different sides. A burning house is the other Tarkovsky image that stands out for me.
6. Mirror - Like too much floatiness, but it's cool to look at and listen to. That wind through the plains part at the beginning is stunning.
7. The Steamroller and the Violin - Nice, cute, but too long for what it is doing, a problem Tarkovsky has overall. That red tho!
8. Nostalghia - Tarkovsky's formalism goes a little too far for me here. It's all ideas, very few people who feel like people.