I still say a wizard's at will is heavily influenced by the tiers. I can expect them to retrain power right before jumping tiers so their at wills differ in power at different levels.
Cloud of Daggers B+/B/C
CoD is awesome at the heroic tier. Later on autokilling minions 1 at a time is too dangerous and insubstantials are rarer, usually low HP, and vulnerable to something other than force.
Magic Missile B-/B/B+
Like CoD but less minion kill and better range. Chances are when you are using this, your attack resources are low so you might as well be 15 squares away.
Ray of Frost C+/B+/B
RoF targets a bad defense so you'll need a boost to spam slow on non shrimisher/lurker. The 2 cold feats help, especially if you have an cold vs Ref encounter or daily.
Scorching Burst A/A-/A-
Kills 50-75% of the minions of a group without using an encounter or daily by turn 2? Where do I sign? Too bad by level 15, wizard should have so many AOEs.
Thunderwave A all around
Nice at heroic, range gets better at paragon. Chance are that you use this every time you get damaged.
Illusionary Ambush B/B+/A
Your only anti artillery at will power and the only one that hits Will. Not bad vs Solos either.