I think it would be hard to answer this because it's pretty subjective. With telephone dating, your first impression would be the message the person leaves, similar to a tagline on an online profile. Online you get the chance to screen through a good amount of thumbnail images(some sites) while telephone you'd have to go through message by message 1 by 1. Personally I've liked online better because you can browse through more people faster and be able to read what they have to write about themselves, however, the "tone" that you read what's written is what you interpret in your own mind versus the actual tone they're using which you can hear over the phone. I've read some rather "intelligent" profiles where the person turned out to be not so intelligent in real life..lol.
But what I think ultimately makes whatever chosen method to be superior is your own experience and intuition in being able to weed out the incompatible ones.