Personally, I find the TCR the top. I also find Greg Susongs Riverboat priceguide an excellent resouce. The prices are inline, and the pictures are invaluable. Offical guide is also very good, and also has alot of pictures. To me, the books that I would always have are as follows (not in specific order)
The Chip Rack
The Gaming Table
The Riverboad Priceguide
The Official US Chip Priceguide
Now that we have the top 4, you can then add the Colorado Priceguide, Florida Priceguide, Caribbean Priceguide, Aruba, Puerto Rico Priceguide, Illegal Chip Priceguide, Atlantic City Chip Priceguide. Ok, theres more, but they'll probably need to wait until next month!