War and Peace, hands down. I'm still very, very late with the review - I thought I'd to it on my and author's shared birthday but again, other stuff happened.
What helped me get through this giant was the rule I set. I just started internship and had about an hour of commute one-way. I decided to read only on train or while waiting for one on the platform, and finish the chapter at home I didn't end it on the train. A little less than two hours, five days a week. I finished it in four weeks exactly, cover to cover. Your average highschooler back home (my class got assigned Quiet Flows The Don as the final-year-epic-length-Russian-book instead, but I've heard other experiences) is not able to finish it in two-and-half months of summer break.
(Yes. Yes I was carrying the brick paperback around in my bag. Yes, I'm probably insane.)
Anyway, I liked it way more than I thought I would. I definitely liked it more than Anna Karenina. I should give my father's favourite - The Cossacks - a try one of these days.