I won't vote; it's a trick question, everyone is good in their own way. My spell preferences are: level 1—slow, haste, bless, shield, stone skin, magic arrow and very rarely curse.
level 2—both lightnings, visions help sometimes, blindness is not bad and fire wall, maybe I missed something else.
level 3—for necromancers my favorite is raise dead, fireball and ice ring I use rarely but still, oh and combat TP.
level 4—chain lightning, meteor storm, resurrection, prayer, clone, town portal =) less often killer and inferno and depending on the situation armageddon (o5 something I missed well it's not that important)
level 5—fly or dimension door, I really love implosion :D and I think if possible I'll put titan' same here—it's some kind of cheating already =)))
P.S. pardon my bad memory, forgot about berserk, and worse is hypnosis since you need quite a decent strength

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And if you're not into magic, it means you only play Heroes with noobs! :smile33:
P.S. Whoever disagrees leave a message for me here.

But as for me, if I get or see the sphere of banning on the map, I won't level up magic at all, so who will be the noob then? The mage who pumps up all sorts of magic and wisdom against me, leaving no room for skills like defense and attack, well or why is logistics bad then?:) with the sphere it's better to pump a warrior (without inclinations toward magic) IMHO!