Eh, none of the Heisei movies past
King Ghidorah should be "highly recommended." and
Mothra and
Spacegodzilla in particular should be skipped
. They're essentially the negative stereotypical image people have of the franchise. Same thing for
Tokyo SOS, Final Wars, or Destroy All Monsters.
I think the best starting out point is just the films between 1962 through 1968. They're usually referred to as the "Golden Age" for a reason, as most of them are pretty respectable and well made films.
Anyways, there was a poll on TV Asahi over in Japan for fans to vote their favorite monsters and films. The results aired recently, and some of them might surprise you.
Favorite monsters (Godzilla excluded)
Favorite films