im considering making a non-mage caster

[Fobbon]

In my (wholly unbiased) opinion, necro would work best if you're starting untwinked. I rolled my necro as my first character and have never regretted it. Oblivion is right, the first 12 levels or so (basically until you get your second Darkness spell and Heat Blood, plus your mana pool is finally large enough to support fear kiting) are pretty rough. Expect to have to help your pet tank mobs, especially on the back half of spell circles (6,7,10,and 11). Once you get over that hump, though, you tend to feel more and more powerful with each spell level.