Voted for larger world and more content because those were the two things that I loved from the first Wasteland and really, from most every other open CRPG that I've played.
The others have merit, too, and here are my own thoughts:
- Expanded character dialog and voice acting
Is it possible to just have the expanded dialog as a separate choice? I don't mind playing a game without any voice acting whatsoever as long as everything else holds up. But I'm totally onboard for more dialogue options, more writing, and don't mind reading all of that sexy text.
- Expanded audio, but NOT voice acting
I'm also all for ear candy! Especially music-wise, but definitely prefer a bigger world.
- Enhanced graphics and 3D models/textures
I'm pretty ambivalent when it comes to this. If a game is fun and has this, I'd consider that a plus. If not, but it's still a lot of fun, then there it is. Am curious, though, if there might be any consideration towards mod support (or toolset support if one is eventually released) to make it easy to modify these assets by fans in the same way that the Elder Scrolls series has done?
- Enhanced NPC portraits and equipment artwork
Again, same point as previous. I'd consider it a bonus myself, but I won't complain if my Ion Blaster looks shiny and new onscreen as I create blood sausages.
- Porting to mobile (iOS and/or Android)
Personally, I'll be playing this on a PC, but it wouldn't hurt to see the game on more platforms especially on mobile.
- Enhanced special effects (explosions, etc.)
This also falls under the eye candy categories above for me. If it is has Michael Bay crying in his sleep from seeing the petrol fueled majesty of Wasteland 2's explosions, I won't complain.
- Create and old school 8-bit version
I'd probably be pretty excited to see this, or even if it's only as a special stage in the game such when you jack into a computer and see it rendered in...8-bits.
- Mod kit
It would be nice, but I also would hope intuitively easy to use. The tile-based stuff used in NWN was ideal for pushing out dungeons on the fly and the way NWN's toolset also handled dialogue trees, quest construction, etc. was head and shoulders above the scripted mess that Elder Scrolls uses IMHO. I'm not saying make it Adventure Construction Set easy, but the shorter the learning curve, the faster fans can start putting out their own apocalyptic add-ons for everyone.

- Other mediums (card games, board games, pen & paper RPG, collectables)
I'm just happy that inXile has even mentioned a paper manual and a cloth map in their Kickstarter. I'm not sure about seeing it in "other mediums", though. It certainly would be great, but if it's going to detract pulling anyone off of the main game to work on content for this, I'd be against it.
And thanks, inXile! Hope to see more ideas from everyone on Wasteland 2!