JayF, the one thing about post WW2 modern armor is that many books suffer from "jet lag", that is information is quite dated after major historical combat operations. While many smaller nations do not have a lot of turnover in their armored formations, countries like the US, UK, Russia have constant and near continuous upgrades as lessons are learned by deployments.
A tank like the Abrams changed considerably from its initial production to its Army-wide fielding in the 1980s. Then the tank changed after combat in Desert Storm and was upgraded through the 1990s. The tanks were more modern versions when OIF began and then went through upgrades during combat in the 2000s.
Jane's is probably one of the better ones since they update frequently. But it depends on whether you want a thick book full of stuff that rarely changes or one that goes in depth into various specific nations' vehicles or a book on infantry fighting vehicles, tanks, etc.