The voting sure is close... (I just had a flash back of American Idol Season 2, Clay VS. Ruben) LOL
I wonder if this might help... they both can fit a ton of stuff, but Ergo has a slight edge in terms of amount it can fit... but keep in mind, things carried in a hobo style bag can get "lost" in the bag because the bottom isn't structured. Ali, on the other hand, has a "belly" compartment in front and you can put your mini skinny there. Ali is also more structured than Ergo.
I'll be interested in seeing what you decide! Keep us posted. Oh, and if you decide to get both, I won't be too surprised either.