As we are coming up to Pearl Harbor Felton has a really, really good recap of the pre-German-US war activities. For all its failures FDR did prepare really well probably inspired by the unpreparedness of Woodrow Wilson in 1917 (does he have an acronym?)
In my view apart from TG Mark Felton and Greggs Automobiles and Aeroplanes are the best at doing original well thought out research as opposed to just presenting what is known.
But that is just my 2 cents.
Marc