I see each of these networks as useful as they are venues where people go - if you are a social networker, you are primarily interested in getting to know a lot of people, the people you are looking for could have a home (profile) in any of these venues, they might be where you least expect them :-)
Social networks could also be seen as tools, to help you find a community where you can meet new people and engage them in conversation / or like a pub crawl if you are the partying type ! I've added my profiles so you have atleast one connect there you can wave at already - if you want.
I notice with Ojeez that they have a fledgling set of networks building
up and the older interface is being changed over for a newer design -
so if you haven't been there in while (like myself) it might be worth
popping by again and updating your profile there.