Ask just about anybody what they consider to be the best dictionary, and almost invariably they will respond without thinking: "Oxford, of course". Many people take a fairly condescending attitude to the alternatives.
I take a different approach. I take a fairly condescending attitude towards people who don't use dictionaries. Sure, it isn't quite as important to be able to flip through a well-worn tome to determine how to construct words such as "condescending" or "ubiquitous" as it used to be. Spell check is...[just a sec...]... ubiquitous... these days, and we just don't need to look things up as often as we did a few years ago.
But some folks don't seem to be able to use the darn things at all. Never mind spelling. They just don't know which words to use. The other day, someone who should know better asked me the difference between "affect" and "effect". I gave an off-the-cuff answer but said that it was best to check in Strunk & White's "Elements of Style" for guidance on their precise usage. I pulled the thin volume from the spot on my desk where it lives with other essential materials, but no-one present had ever heard of it. I mean, really! I don't know how anyone could possibly get through life without hearing about this book. It's a classic. I don't open it up as often as I used to, or perhaps as often as I should. But when I was developing my writing abilities, for fun or for profit, I found it to be invaluable.
Oh, and which dictionary do I use? Its a "Collins" paperback, and I'd put it against a similarly sized Oxford any day. In fact, no less a wordsmith than Anthony Burgess claimed that Collin's dictionaries surpassed the Oxford in the ultimate linguistic test; the Collins definitions of certain four letter words were much more lucid than those in the Oxford. That's a trial by fire that's good enough for me.