Wizard:
Ray of Frost: I don't like the Slow Effect from Ray of Frost to much, but if you are playing a cold-mage with the appropriate feats it can become quite good.
Magic Missile is underrated in my opinion. The Range 20 can really help in the beginning of a combat, the damage is very good and sometimes you just need a damaging power for just one enemy. Also you can use the cheap gauntlets that adds damage to a basic attack. If you play a Wizard with primarily Area Attacks, then it is good to have at least one power that can help you out without hurting nearby friends...
Cloud of Dagger is a superbly anti minion power, but for some reasome I simply don't like it even though I play an Orb Wizard myself.
Scorching Ray & Thunderwave are both superb and every Wizard should take at least one of them!
Overall I find that the Wizard is the only class where I really have problems deciding which of the awesome powers I should take.
Fighter:
Cleave: Great Minion Killer ... if you lack a controller or just want to hack Minions to pieces, then take it!
Reaping Strike: It's a bit meh for me since it is only good if you miss and even then it's not too much damage for a REAL opponent. Still, if you have a two handed Weapon and only one enemy then it is surely better that a Basic Attack. One more problem ... it sucks for one-handed Weapon Fighters.
Tide of Iron: A must for every Shield Fighter! For everyone else absolute useless
Sure Strike: It would have been an good alternative to the other At-Wills if you would have kept the Strength for damage, but without it ...
While the Fighter have some interesting At-Wills, he mostly have no real choice which to take and humans have to take one at-will that they don't really need (at least till the martial handbook is out).