Dragonborn — Useless stat bonuses and a redundant racial ability make this a poor choice. The only reason to consider dragonborn is if you're a staff wizard and want some added constitution synergy from the healing surge bonus.
Dwarf — They have bonuses to two secondary abilities, making them an ok choice for someone planning to take both orb and staff mastery. Their racial abilities aren't much use unless you plan on stand in melee a lot, and their low speed will make it harder to avoid that.
Eladrin — The best choice for a wand wizard. In addition to the stat bonuses, they have useful skill bonuses and an encounter teleport for getting out of trouble. Their free skill is always useful; you can invest in perception to avoid surprise, thievery to make up for a party not having a rogue, or stealth so you can get combat advantage. The longsword proficiency is also good for anyone planning to take Wizard of the Spiral Tower. There's a lot to be said for this race.
Elf — Before Adventurer's Vault, this race was considered to be 5 stars for orb wizards because starting with 18 wisdom and going demigod to end with 28 wisdom was the only way to permanently stun lock normal monsters. Now a Wizard of the Spiral Tower with a phrenic crown and cunning blade can permanently stun lock solo monsters with a 24 wisdom, meaning elves aren't necessary anymore. Still, the wisdom bonus with high speed and their reroll racial ability still makes them a good choice, letting them reach stunlocking earlier or with less of a stat investment.
Half-Elf — While the constitution may help staff wizards, there's not much else to be said for them. The only other class with int-based at wills is the swordmage, meaning you need to stick to weapon powers with a staff or pick up proficiency in a blade and swordmage multiclass to take advantage of dilettante. The charisma bonus helps with some feats.
Halfling — While their stat bonuses are only a small help to wand wizards, their racial bonus against opportunity attacks and power to avoid being hit are great for getting out of tight spots. Small size doesn't hurt a spellcaster, either. The charisma bonus helps with some feats.
Human — Your stat increase will go into intelligence, so you won't get a bonus to your secondary, but the free skill and feat are nice, and an extra at-will is great. Action surge is huge if you use an action point before a large area attack.
Tiefling — These are the most accurate wizards; they have an intelligence bonus, a bonus to hit bloodied creatures, a power that can give them another bonus to hit against someone that hit them, and a feat to get another bonus to hit with fire spells (or every spell with a flaming longsword, for WotST). The charisma bonus is useful for some feat qualifications, to boot.
Forgotten Realms Player's Guide Edit
Drow — Like a halfling, the stat bonuses are only a minor help, but the racial powers are great, letting you either get out of a tight spot and have combat advantage against those who put you in it or have an enemy grant combat advantage to everyone in your party.
Genasi — You're not likely to make use of the strength bonus, but the racial powers are all great. Fire punishes someone who runs up to hit you, earth knocks prone everyone adjacent so you can get away, water and wind are good for positioning or fleeing, and storm makes your area effect lightning and thunder powers terrifying.
Dragon Magazine Edit
Gnoll (Dragon 367) — They have two secondary stat boosts, good mobility, and one useful power- blood fury can give a nice boost to area attacks. Their other powers are melee-only and thus not very useful in most situations.
Races appearing in the following sources were not intended for use by player characters. Most of these have very limited racial options. Consult with your DM before creating a character using one of these races.
Monster Manual Edit
Doppleganger — Same stat boosts as a tiefling, but none of the fun to hit bonuses. Still, Change Shape can be fun, and no intelligence boosting race is all that bad for a wizard. Easy access to charisma feats and a racial Will bonuses are nice, too.
Gnome — Again with the tiefling bonuses- intelligence is nice, charisma helps with feats. It's their racials which make this nice; if they have a decent stealth they can start many combats with combat advantage, and reactive stealth is perfect for fleeing a bad situation without taking opportunity attacks. The small size won't hurt you, but the 5 speed might.
Shadar-Kai — Similar to the eladrin, without the benefit of racial weapons and an extra skill. Their teleport is shorter but leaves you insubstantial; it's hard to say that one's better than the other.