Thanks. Forgot about looking in the System Files folder. We now have a universally available form of Garamond -- at least for 10.4 or later.

Some of the other fonts look promising. I will make a test style sheet and see what they can do.

Now, if the glitch in OpenGL (OS X) can get fixed....

Of the following lines, only the first one gives what I was expecting:

Style[TraditionalForm[a + b <= 1], 
 FontFamily -> "Latin Modern Roman"]
Style[TraditionalForm[a + b <= 1], FontFamily -> "Latin Modern Math"]
Style[TraditionalForm[a + b <= 1], FontFamily -> "Computer Modern"]
Style[TraditionalForm[a + b <= 1], FontFamily -> "LaTeX"]
Style[a + b <= 1, FontFamily -> "LaTeX"]

The purpose was to imitate the standard TeX look.

Thanks Jennafyr for sharing that list. @Silvia Hao has made this comprehensive infograph of the new functionality in M10.4 using ClusteringTree: