I'm not really entirely convinced with this argument about wizard at-will vs invoker at-will personally. At best the difference is VERY slight indeed. Wizard at-wills do NOT suck. Unimaginative wizard players may think so, but that is their problem.
Avenging Light - Very marginal difference from MM. Some will argue the 2x range of MM makes up for this. One thing is for sure, if you NEED a range 20 at-will, then AL is worthless in that situation and invokers have NO range 20 at-wills.
Grasping Shards - attacks fort and is best compared with Scorching Burst. Definitely more controllery, we applaud, but slowed is a conditionally useful effect, damage is ALWAYS useful and SB wins hands down on that.
Sun Strike - Compares favorably with Ray of Frost. 1 slides, the other slows. RoF is a FORT attack, so SS is slightly better in that respect.
Vanguard's Lightening - Very slightly better than SB. The conditional damage isn't a huge factor really. Still a bit nicer.
Divine Bolts - Yup, it is better than either MM, RoF, or SB hands down.
Notice I haven't even compared with the 2 BEST BY FAR wizard at-wills yet, CoD and Thunderwave. Invoker has nothing to compare with Thunderwave. Some love it and some hate it, but in my DMing experience I've seen Thunderwave used to devastating effect a number of times. It certainly adds a dimension to the wizard at-wills that invoker totally lacks. CoD is always a bit of a hard case to judge. Could be compared with Sun Strike or AL, but it does again have its own unique uses.
I just don't see that overall wizard's at-wills are worse than invoker's. Imagine swapping the whole list from one class to the other with the obvious primary stat switched and wizard would not become a more powerful class. It would certainly become more powerful if you could pick and choose between all 10, but then so would invoker. I would venture to say if you had all 10 to choose from any given player would choose from both lists depending on what they wanted to build. The worst you can say is that MM and SB would be relegated to special uses (long range fire and situations where you WANT fire damage specifically).
People seem to WANT there to be a power creep argument. Well, if PHB2 is power creep it is the continental drift of power creep! The new classes and races are interesting and different, but hardly different from the old ones power wise.