I am very fond of the fonts M.R.C. van Dongen used to typeset his book LaTeX and Friends. I believe it is the same as Hatcher uses for his books (for instance Algebraic Topology), and also the one in which the Princeton Mathematical Companion is written. It is called FF Nexus, and it costs 200$. Here's what FF Nexus looks like.
Is there a free alternative, that contains very similar fonts?