The IM war is heating up. What's your pick?

At this point in time, Yahoo Messenger with Voice version 8 is still in beta. It provides an extension mechanism through plug-ins, which can be downloaded from this gallery and developed by third parties using the publicly available Software Development Kit. Here is TechCrunch's post.

The way I read it, it seems Microsoft is going for a somehow business-orientated, closed and tightly controlled environment where users can easily share their data, files, contacts and content between the different "Live" applications, with the kick of having a centralized and up-to-date information repository. It seems though, users will probably need to use a good part of their Live products and services set in order to really benefit from the experience.

Yahoo, on the contrary, seems to be betting on a more entertainment-orientated, open, fun and friendly environment where users can customize the behavior of their applications (and therefore the way they share content and interact with each other) and add more functionality into the messenger application itself (as opposite to having several different applications sharing data from a unique repository).

Oh, and yes, Yahoo is also getting more serious about VoIP promoting their cheap PC to phone calls. This puts them in direct competition with Ebay's Skype, which has also been adding very cool new features as SkypeCasts, video support and more. Google talk seems to be slowly kicking in too, may be differentiating itself for its recognizable simplicity.

All this seems reasonable given the positioning of each of these companies. What's your pick?