If I went the pedal route, I'd go with the Electro-Harmonix effects. I did like them; they have the right balance between control and complexity, and the sound is natural. I found that they didn't color the tone of the instrument. But I never specifically settled on a delay. However, I'm not too fickle, and would probably be perfectly happy with DSI's onboard effects. I even find the Evolver's delays to be sufficient. It's the form that I'm picky about.
For anyone who's interested, here's a demo of the Korg pedal with a Prophet 12: