Agreed with many here. There are two total different situations to consider when debating which race has the best powers.
One of the major additions to the design of 4E is purposeful action economy. The best combat powers improve your ability do to more stuff in a round. Here, you have three big winners: Fey Step, Dwarven Resilience and Breath Weapon. Each one is basically a trade UP of a Minor Action to a move or Standard Action once per encounter. Human At-will and Half-Elf Dilletante give you flexibility, but not economy. Second Chance, Elven Accuracy and the woefully inadequate Tiefling Fury (or whatever it's called) give you the ability to do an action better, but plenty of feats, conditions and tactics do that. In combat, do you want to move/evade, heal yourself or blast things? There's your best combat racial power.
Out of combat, the whole field changes. Elven Accuracy, Tiefling Fury, Dwarven Resilience and Second Chance are utterly pointless; they require attacks. Human At-Will, Half-Elf dilletante and Breath Weapon are fun for flavor-texting, especially with wizards, but are mechanically not that hot. So we're left with Fey Step, again! A 5-square teleport is just freaking handy in any situation and is the only racial power guaranteed to have effectiveness both in and out of combat.
Winner: Fey Step. By a lot.