No opposition from me. I'd have to agree with you. (It's very distracting to type a post when I'm looking at your sig, )
In terms of games, merchandising, and long-term interest, it'd have to be Pokemon (as it already is).
It just has a simple model of pumping out many little critters to appeal to the masses.
Show/story wise however, it would be Digimon, hands down.
Pokemon's deficit in its show is they are generally predictable, kid-friendly episodes that feature a "character of the day" and have no overarching story or depth (aside from Ash wanting to be a Pokemon Master in whatever league). Digimon has a complete story that plays out over the course of its season/series, there is actually character development and more exciting plot conflicts to address.
In the 'art' category, it's a toss up. I am compelled to say that Digimon has better art because they are more radical in design (unique) and detailed, but a few designs are whack to me.
Pokemon uses a simple, streamlined concept that carries over to every Pokemon. It's like vanilla ice cream. Not bad, but not great.
Also playing into popularity of Digimon are its renditions, I found the first seasons involving 'Digidestined' enchanting, while the series about fusing with Digimon (season 4?) to some battle armor unoriginal. In fact, I stopped watching a few episodes into S4 and haven't seen another Digimon series since.
The team behind Digimon sort of gave up and didn't have a strong enough premise to keep going like Pokemon's "train and catch new Pokemon" basis, hence Digimon's popularity peaked, then dropped off after the 'fad' was over.