Yes, text adventure games go beyond Infocom, although they won the era. There's Magnetic Scrolls, Melbourne House, Level 9, and (yes) Legend, which shares DNA with Infocom in the form of prolific alum Steve Meretzky. Back in the day, everyone was getting in on text adventures; even Electronic Arts published one.

That said, I would go with an Infocom game for your first, as the later ones especially were very well-designed and tended to be fairly forgiving. A Mind Forever Voyaging or Planetfall are good choices. Planetfall has a sequel, if that makes it more interesting to you. I would avoid Zork to start; it's a good game, but there was a lot of evolution after 1977.

The Hitchhiker's Guide to the Galaxy is one of the medium's crowning achievements and you should probably wait to savor that one.