This isn't a totally useful answer, but that's ok.
In terms of security, I'd gamble that they're all even. Useability is the more important measure, because complex interfaces often lead to human error which causes insecurity. But, if used properly, they're just as secure. Probably.
It might be an idea to run snort on there, too. Snort can detect or, if you want, block attacks based on signatures. It's also useful to find out who's using MSN Messenger, Battle.net, and other stuff.