Digimon Adventures and Digimon Frontier were my favorite childhood TV programs. What I loved about this show was the character development, and how each episode focused on a specific character. I also appreciated the fact that the Digimon are actually able to speak (in Pokemon, the monsters just say their names, which is super annoying).
When comparing Digimon with Pokemon, I honestly believe Pokemon is extremely juvenile, and mostly catered for younger kids (ages 3-7). Digimon has a sort of complexity to it that differentiates itself from Pokemon. Audiences develop bonds with their favorite characters, which is common in popular shows nowadays (i.e. Game of Thrones).
Even as a 24 year old, watching Gatomon digi-volve into Angewoman, still gives me goosebumps. =P