I'm inclined to lean toward CC2 on the basis of potential. While it's worth discussing, I don't think it's going to do a lot of good at this point to debate how many "eligible" levels are available for a community pack for either game right now. I can remember back in the late '90s, we barely had any custom levels but proceeded to create CCLP2 anyway around 2000-2001. The pack turned out quite well and inspired so many budding designers to create levels of their own that CCLP3's voting pool dwarfed CCLP2's by quite a few magnitudes. That's what community packs are great for - exploring new ideas and design styles just enough that someone who may have been skittish about their own creativity takes that first step.
Right now, CC2 doesn't have a set like that. The original game was created back in the late '90s, and the editor was limited enough that most of the levels were built with the 10x10 map size. Some of the elements were barely used in the stock game's main campaign, which is a shame. I'd wait a year or two to begin working toward voting for a set, but just from playing some of the levels that have been made, the quality far exceeds what was available for CC1 when CCLP2 was assembled. For anyone who's hesitant to let go of the familiarity of CC1, I'd recommend playing through a set like Joshua Bone's Walls of CC1 and see just how much potential there is to be uncovered in CC2. The sky's the limit if we're willing to invest in it.