I like phpizabi it has a really cool look and feel and many features like myspace and some that even myspace doesn't have. It is free and easily customizable. The last time I was tinkering with it, it had a problem letting users add contant to comments. i looked everywhere for an option to turn this on/off and didn't find it. Plus I am not sure how easy it is for a user to customize their layouts. It is an awesome script though. And it has been updated quite a bit since I last used it, so I am sure (or I would hope) they fixed these issues.
http://ww2.phpizabi.net/
Worth looking into.
Also Dolphin 6 looks pretty good. It has some awesome free plugins/features and even better paid ones. Also worth a look.
http://www.boonex.com/products/dolphin/