=VOX=
The thing I like about VOX right now is that it feels both small and large, a very inclusive community. The "neighborhood" metaphor and the "[this is good]" check box make everything seem so friendly and supportive. I'm sure the userbase is exploding, especially as more people from around the world can now create accounts.
I also love the support for sharing more than just words; photos, images, music, videos -- they all add to a richer blogging experience.
I am also happily an LJ user, but that site is different. With communities and different levels of filters and security, it can sometimes seem isolating. That can be a good thing (I'm not sure how much I like the whole world able to read about my life), but it's also harder to "meet" new people there. On VOX, I feel like I have a chance to meet some neat folks.

Comments
see, I've put you in my neighbourhood already. haha
I have a Livejournal (abandoned for months), and the experience there was very much one of connecting with people you already know, whereas Vox feels much more about meeting new people.
Welcome to my neighbourhood!
I'm still very active on LJ, but Vox was just something I had to do.
Definitely more friendly.