It's hard to beat the original version of Boggle! It's what the game of Boggle is based around and from which all other variations spring. If I only possessed one Boggle product it would either be this, Boggle Deluxe (see below), or Boggle Folio (which is similar to the original version, but is more convenient for travel and has other interesting qualities).
This is a special 25th anniversary edition of Boggle. It is in a higher quality box, but the real advantage of this edition is the Boggle Bar. The Boggle Bar allows you to attach and reattach pieces so that you can play with the traditional 16 letter Boggle board or choose to use the "Big Boggle" 20 letter board.
As a Boggle lover, I'm a big fan of encouraging an interest in Boggle in as early an age as possible (oh yeah, and reading too!). This junior version of Boggle is designed for ages 3-5 (preschool age). Boggle Junior Letters is perfect for kids who are just starting to learn to recognize words. It's very simple, but educational and fun!