If you want it to be that way throughout the entire level span, necromancer is probably your only choice. Magician stops being amazing at higher levels, and shamans don't get really powerful until the upper 40s. Bards can't just sit down wherever they like and start soloing, there are limitations the same way there are to quad-kiting. Also, after playing a bard for a while, you might wish you were playing a class with some downtime so you can go to the bathroom and stuff like that without dying or having to zone half-way through a kite.
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