If the original book looks good, why not imitate it? Or have you been asked to the contrary?

I would go for Janson, but mind you, the indents look rather long. Also, it would be good to introduce some hyphenation to improve the word spacing.

I’ve always liked the early 20th century Garamonds, considering them to be more truly representative of the quality of old letterpress than more polished revivals. The digital Janson and Granjon also strike me as being a bit slick.

Verdigris, Corundum and William’s Caslon are all sturdy, reasonably authentic “second generation” digital garaldes.
A postmodern Garalde: Oneleigh

Nick, you classify William's Caslon as a Garalde? It's in the lineage -- Garamond, Granjon, Antwerp, Holland, Caslon --, but its separated by 200+ years and the whole Dutch mannerist and baroque.

John, I don't see a fundamental difference in genre between Garamond and Caslon.

American Garamond is a Jannon, not a Garamond. On the other hand,
I think Jannon is more "earthy and rustic" than Garamond. BTW, I once
made a letterpress keepsake about ATF Garamond (another Jannon) using
reduced wine in the ink, and the wine was from Jannon's birthplace. :-)

Like check this out!
http://new.myfonts.com/fonts/storm/jannon-pro/

In another vein, what about a Kis, like Ehrhardt?
http://new.myfonts.com/fonts/adobe/ehrhardt/

--

Nick, I have to say that's quite... drôle.

hhp

Thank you.
Caslon has certain serifs which are more differentiated from the stems, but other than that the structures and proportions are quite similar, informed as they are by the broad nib pen. And many letters are practically identical, e.g. ‘A’ and “a’ right off the bat.
Isn’t that the idea of ‘Garalde’?—it’s old-style, but not Venetian, which preceded it. Then it was followed by Transitional.
Maybe a lot of the similarity is in the interpretations.
Adobe Garamond and Williams Caslon:

I don't get it - what's with the two lines of Times?

hhp

You mock.
I merely state conventional wisdom (which I take to represent broadly understood meaning), that equates Garalde and Old Style as a single genre which includes Caslon.
See for instance British Standards Classification of Typefaces (BS 2961:1967)

Thank you for your interesting contributions, Nick and Hrant.

Janson/Kis is a great typeface. The two most successful digital “revitalizations” are Kis Antiqua Now and Equity (the latter based on Erhard).
Other recent digital garaldes are Lyon, Erato and Merlo for example.

The only thing I would offer about the original poster's question is to recommend that he look at offset printed examples, and not rely only on the screen.

Caslon is obviously in the line of Griffo-Garamond, and an old style, as Nick mentions. It also has some significant differences, as John notes. Whether to classify it as a separate category or as a variation seems to me somewhat arbitrary, and dependent on the purpose of the classification. I haven't studied the various "Dutch" and French faces from the previous century, the 17th century, so I don't know how much they share with Caslon.

I'd heard it said that the "goût Hollandaise" came from the Dutch being accustomed to black letter. Thus the Dutch roman types tend to be a bit blacker with shorter extenders. The aesthetic of Caslon is obviously different from Garamond, with Garmond being more delicate and elegant, and Caslon having a more robust, feet-on-the-ground feeling.

Bringhurst points out that "Baroque" faces, which is where he puts Caslon, have more variation in stress (mixing oblique and vertical stress), and are still more modeled and less calligraphic than Garamond. I think the latter is particularly important. I see in Nick's comparison lines that my Caslon is generally a bit narrower than Adobe Garamond. My proportions are pretty true to Caslon's Pica 2, and to me the somewhat narrower proportions is an important characteristic also. I should also confess, for clarity in this discussion, that I think Caslon's g's are ugly, so I drew a shape that looks more agreeable to my eyes. It is closer to Garamond than Caslon's own letter g is.