I'd say the phenom, but I'm not sure if triple core processors are useful right now. I mean, when dual SLI ndivia videocards came out, they weren't very useful except for doom3. And when dual core processors came out, not many programs could take advantage of it.
This may not be the case for triple core processors, but I wouldn't know because I haven't shopped around for a pc in ages (and shopping around for technology is the only way I learn about new technology.

)