Listen, as an Affliction Warlock I certainly can understand the Pain of the Tab-Targeting we have right now. But how on earth should the Computer know which Target I want to choose next? They cannot read minds, ya know.
7.1 improved it a little bit, but I mostly use the Mouse now for targeting, you just need a good Name Plates Addon (I like Tidy Plates, neat and tidy
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IMHO a lot of the "Klickers" are dependent on the Tab-Targeting. Switching to the Mouse and Keybindings is the best way to precisely target the Enemies you want, especially if it gets Hectic and fast-paced. It is a hard switch, but worth it.