Just an opinion, but hopefully a considered one (studied photography at art college, also @18yrs)
I could recommend a handful of personal favourite photographers, maybe even pick one out, but I fel that I made that mistake at art college. Received (on request) for xmas one coffee table book of one photographer whose work I admired greatly and then soon idolised. Yet looking back, it narrowed my view of what photography could be, so subsequently I became almost defensively derivative of one style/discipline (B/W landscapes and ruins). Took almost forever to get out of that groove. 13 years to be precise. And I still relapse 😬
There is so much variety for a mind to gorge on. Portrait, candid/street, abstract, fine art, advertising, travel, still life, figurative/fashion, landscape, journalistic, wildlife, etc, etc. I can see see the temptation of prescribing one stunning book from a particular lens-swinger. But who to choose? Arbus, Adams, Capra, Leibovitz, Maier, Brant, Mapplethorpe, Araki? I certainly would have a hard time choosing one. So why not a book containing a wider collection of images from number of photographers?
With that in mind, this springs to mind:
The Photography Book (2nd Revised Edition, 2014)
Hardcover: 576 pages
Publisher: Phaidon Press
I have the first edition and it’s a real joy. You can get lost for hrs. If I had to criticise, I suppose (for personal preference) it’s a little light on landscapes/wildlife, so I’d probably package it along with something like this or Nat Geo as mentioned.
But, if purchasing just one as a starter (and with hindsight) for me I’d go for something like ‘The Photography Book’