I was going to vote for the Silver Surfer story, but the GL story intrigues me a little more. I think Marvel's aliens are a little more established, and it would be interesting to see how the GL's mix into that.
"As you know, there are 3600 sectors of space that the Green Lanterns take care off," Ganthet said to Hal Jordan and Kilowog as the stood in the centre of the council room. A dozen other Lanterns stood nearby. "But these are only those that we have explored and have had contact with. Today we have a new sector."
"Interesting," Hal Jordan said. "Whereabouts?"
Ganthet pointed to a section of space. "Beyond the Source Wall."
A gasp followed by muttering took over the chamber. Ganthet watched them and waited for silence.
"We are sending a team to breach the wall and to investigate this new universe," Ganthet said.
"Breaching the wall is impossible!" Kilowog blurted out.
"We thought so too," Ganthet said before pointing to a long silver board lying on the floor. "Until THAT came through the Source Wall from the other side."