Jman is right big growth. Any out of box script probably wont handle it.
Dolphin>> ZOMG! By far the nicest looking script out!
Here is is in action at
http://suicidedolls.net/
It took me literally 4 weeks to debug it. very little or zero tech support for it.
It was a fucking mess. I finally go it working good but I'm afraid to actually launch that site with Dolphin running it.
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1. PHPFOX :
http://www.phpfox.com/ Best forum support, most mods and ad ons but out of the box content rich, stable and amny themes you can go with.
I'm running it on two social sites for the last few years. Latest stable version has so many cool features.
2. ABLESPACE :
http://www.abledating.net this was a glorified dating script.
Members cant alter their profile design. People use myspace as a barometer and love to change thieir page design. way overpriced
3. HANDSHAKES PRO :
http://www.dzoic.com/
This would be my second choice althogh, no user profile customization capabilities.
4. ALICIA (free) :
http://www.phpizabi.net/
Came a long way over the years, still lacking flexibility/member use ability.
First thing you should always check when buying boxed software is their support forum. If its active and timely reply to support questions then thats a good sign.