It all depends on what about each one. For example. Digimon originated from the small Tamagotchi-like battlers that you carried around with you. Then there was the Pikachu Jogger thing. Equivalent of the Original Digimon (I still have mine :P). Digimon wins that one. Now, Games: Pokemon Red, blue, Yellow, Gold, Silver, Ruby, Sapphire, TCG, Pinball (2 of them), FireRed, and LeafGreen. THEN! Pokemon Stadium, Pokemon Stadium 2, and Pokemon Colosseum. Digimon has the boring (and at times very confusing) Digimon World 1, 2, 3, and 4 (probably more). Pokemon wins that one. Card game: Pokemon wins. Although, Digimon started the Yu-Gi-Oh format of battling. :P Pokemon is the best TCG yet (even better than Magic). And last but not least, cartoon: Digimon is more oriented towards early-teens, whereas Pokemon is oriented towards smaller kids. The Story is better and more serious on Digimon, whereas Pokemon tends to be more comical. Digimon wins that one.
Overall, I like Pokemon Better. That's just my opinion! :P