I am partial to the Foundations series for a lot of reasons... When I was a first year resident I came on this board and a wiser senior resident told me to spend my money on these books. I am glad I listened. Sure, some are better than others (there are only a few I would NOT recommend), but they are ideal for residents IMHO. They include almost every entity you will come across, and give you enough info on each one that you will have a clear understanding of how to diagnose it and what the DDx is. There are nice tables for each entity that give you the clinical presentation, incidence, general features; then another one that gives you classic histology, gross, IHC, and DDx. If you are in a hurry you can just refer to the tables. Also, they spend a lot of time in general on specific variants of each entity, and almost always provide great pictures- usually many/entity, including all the variants and focus on critical features for the DX.
I had Rosai as a first year resident... but once I got a foundations book for whatever rotation I was on, Rosai got left in the dust. I can't even remember the last time I opened that book.