The OED is a historical dictionary, which means it shows the meanings of words as they developed over time. People *use* it as a standard, but it does not set out to be one, and the [editors of the OED discourage people][1] from deciding whether or not to use a word based solely on its inclusion in the OED.

The New Oxford American Dictionary is not a historical dictionary, but a dictionary of current English, and is much smaller than the OED in the number of terms covered. (If you have a Mac, you already have this dictionary, because it's the dictionary used by the Dictionary Widget in the dashboard.)

If you are looking for a dictionary that set itself up as a standard, especially for scientific and technical vocabulary of the day you might look at the [Century Dictionary][2](commentary at link). It has not been updated for about a hundred years, though. 

The bigger question is: what do you want a standard for?

- To tell you whether or not something is a word? No dictionary will tell you that, only usage. 

- Etymology? The OED is among the best for etymology, although there are other sites that have better ones for particular words (and despite the Century's age, its etymologies are on a par with the OED). 

- Advice on correct or accepted usage? You'd be better off with the Dictionary of Modern American Usage. 

- An impressive book to put on a stand? True dictionary aficionados like Merriam Webster's Second International (rather than the third), as a prestige thing. (Or again, a copy of the Century, although that's ten volumes.) 



  [1]: http://www.oed.com/public/collecting/collecting-the-evidence
  [2]: http://books.google.com/books?id=A3gAAAAAYAAJ&pg=PA315&dq=%22the+century+dictionary%22&hl=en&ei=cCtZTfXTB5SftweXmrTuDA&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFMQ6AEwCQ#v=onepage&q=%22the%20century%20dictionary%22&f=false