gamecp is a pile. I had used it back when I was first starting the game venture. The support is awful, the owner is rude, and the software was extremely buggy. Not to mention he has been banned from several forums for being a jerk/screwing people over.
The plesk module is not designed for full game server usage, just a handful of games, same as the cpanel addon
You can not serve WOW games, this is reserved for blizzard only, no independent gameservers can be run.
have a strong look at tcadmin.com, that is who we currently use and will continue to use until the world ends. Their support is fantastic, the product is solid and they are very open to improvement suggestions. You cannot ask for anything better