[Lytspeed]

I don't know a lot about Prima, but if it's like other poker networks (iPoker, Doyle's, etc.) then they probably are all interfaces to the same games. As for why they have several portals, think in terms of franchises. Various people own and operate the portals, and they all connect to the same network. Owners probably get paid based on the number of visitors they attract to the network.

If this is the case, the only reason to choose one site over another is personal preference. If you like one site's graphics better than another, then you should use the site you like better.

One more thing ... you will probably find that if you try to register with more than one of these sites, they won't let you use the same username because they are all connected.