Maxed wand of magic missile. You have a gun, that never misses, with decent range, which effects damn near everything. The other four get to fit your char's personality. Maybe Tasha's Hideous, if you're that sick. Enchantments, used properly, are just mean and funny.

Scrolls? Depends on how you want to use them. Whipping a scroll out in battle isn't my thing, and putting utility spells on paper is a good way to free up your daily list for signature ass kickery.

Well, if you could swap out one of the wizard levels for rogue, you could always go for the Mindbender, one of my personal fav's. Not only will you have a permanent charmed person handy but you will be on your way to having a handy thrall. Five dominated characters to do your bidding while oozing charm works wonders!

Im thinking more of the kind of spells that this character uses will define him.

I've been thinking something along the lines of a Gnome who loves to use magic jar to have fun with.

A couple of ways to do this:-

'Gnome' could setup an encounter with the PC's were they find the apparently dead gnome's body. With some kind of diary on him explaining some reasoning for the pc's to take the body with them, and his loot. He is of course under the effect of an extended-magic jar ( so 22 hour duration ).

During this time of course he can and will try and seize control of alsorts of random passerby's for his fun against the pc's.

He might need some kind of nystuls' magic aura cast on the receptacle of the magic jar so it appears as non-magical rather than stinking of necromancy.

Alternatively if he is going to be a full on nemesis then he could use it in combat. Perhaps combine it with a mislead spell first, then proceed to magic jar and start doing horrid stuff to the players whilst they hopefully are distracted by the mislead. Maybe he could start with some kind of summon monster spell to provide a pile of potential disposable hosts.

Obviously makes sure he has some kind of continguency pre-cast to get him out of trouble.

Character wise, you just need to nail down his spell list. Perhaps give him the Spell Focus Necro, and Greater Spell focus Necro to make his magic jar abit tougher to save.

Wandwise, not entirely sure. Probably a wand of fire so he could isolate a couple of people away from the party. Magic jar into one of the two isolated people and beat the crap out of his friend.

Also ontop of this if he is to approach people with dialogue perhaps give him a silent Blindness spell in memory. No vocals, or somatics? Who the hell cast that? =)

Could be lots of fun to be had with this.