Probably reverb. Delay makes an echo as in a singular sound wave bouncing off of a wall, reverb is a more subtle echo, like the sound bouncing off of walls of a room, sounding fuller. Personally, I use a delay of about 200 milliseconds that's not a full echo, one that tapers off, as well as reverb. It kind of simulates what it would sound like playing in an auditorium.
The Kids Aren't Alright (it's been a while since I've heard it, but from what I remember) does not have much (if any) delay throughout the solo, and not too much reverb either. There's slight reverb with a very saturated distortion.
"You must stab him in the heart with the Bone Saber of Zumacalis... well, you could stab him in the head or the lungs, too... and the saber, it probably doesn't have to be bone, just anything sharp lying around the house... you could poke him with a pillow and kill him."
- Aqua Teen Hunger Force, The Universal Re-Monster