There is a growing list of fonts which have good polytonic Greek (see, for instance, the list here). Yet, as noted above, only few fonts provide a complete set of specialized symbols: particularly rare are combinations of breve/macron with other diacritics, and epigraphical, metrical and papyrological symbols. The fonts available with the GreekKeys package (particularly New Athena Unicode, but also AttikaU, KadmosU, BosporusU) do provide fuller sets, as does the LaserGreek family. The free fonts Gentium and Cardo also have very complete ranges. Finally, epigraphists may want to download the font Aegean, which includes a very wide range of symbols, including for archaic epichoric alphabets (for details, see here).