Which is better ??

As for as i know it`s Orkut i am using it since first year of my college life..

Facebook is most popular. Most of your friends would be already on Facebook and not on other sites. So despite drawbacks, facebook is most useful for social networking. This is okay if you are cautios enough not to divulge more personal details on FB. For more intimate and personal communication, emailing is best. Facebook is like a village choupal where very private matter should not be talked.

I think all these three are popular and I find twitter and facebook to be user-friendly!

orkut is best all of them.

It differs on the individual's choice.I will choose facebook rather than other social networking sites.