Crane, no doubt about it.
If you don't have a layout yet - well, you'll need some Construction sets to build it, won't you? So, there's the logical reason ;-) And you can "size it down" easily and make a smaller crane which still looks good. I liked the set so much I bought 3. For USD 50 I wouldn't hesitate, here in Europe it's around EUR 50 (on sale) and EUR 60+ (SRP/RRP).
That was your mayor's impartial point of view... *cough*
You'd buy EB's favorite 2006 City set, too, according to the current poll results ;-)
The Crab Crusher is the best of AR so far, I think, and if you happen to have 4888 there might be possibilities to "merge" that sub with the Crusher sub.
I'd say it depends on your priority: start a layout, or expand your divers stuff. But the crane looks pretty impressive on a shelf, too, if you don't have time to build your city yet.
I wonder who made that terrific picture of the crane...........