The value of virtually anything is that which you assign to it; the price is what you are willing to pay for it. If you choose a typeface based on the fact that a prestigious magazine uses it, you surrender your valuation for someone else's. And, finally, your choice of a typeface isn't going to make your prose any more credible or erudite; it can only render it more—or less—readable.

What an enviable dilemma! You'll get a number of
good pointers from professional users of fonts I'm
sure; here are some opinions from a maker:

Brioni:
http://typographica.org/typeface-reviews/brioni/
It's nicely contemporary without being mannered.
Be aware that its generous x-height makes it more
suitable for small point sizes.

Fedra is idiosyncratic, but I believe highly readable.
It also has the wonderful feature of multiple extender
lengths, which allows the accommodation of various
point sizes of text.

Hoefler Text comes with Macs. Because it's very nice.
But that also means it might be too common to pay
good money for. Mercury is a Fleischmann revival,
which means it's naturally highly readable, and a
solid choice in many other ways.

Equity is a nice if conservative design, and its low
price might make it worthwhile, although it can't
be too versatile; you could still use it to add some
divergence from the other workhorses you'll buy.

Whatever you choose, it does sounds like you will
need a wide choice of numeral styles: proportional
& fixed-width combined with lining & "old-style" at
the very least.

hhp

An enviable predicament indeed. Brioni text, Fedra and Fedra sans would all make great choices.

I'll add a couple more to your list: you might like some of the faces that Hoftype produce, particularly Cala: http://www.hoftype.com/node/37 (serif) & Impara: http://www.hoftype.com/impara (sans-serif), both of which would work well together I think. As a little added bonus, they offer the light weights of both for free at myfonts so you can try them out to see how they look.

Many thanks to hrant and penn. I guess that oldnick was living up to his moniker there with some cod philosophy (which doesn't make it any less true I suppose). I appreciate the feedback; very useful to someone who is in danger of getting all the gear but having no idea.

I'll try to come up with new suggestions of
my own, but again, I'm not much of a user...

hhp

Much appreciated hrant. Guidance from someone who has 'been there, done that' is always welcome. I am also looking at those fonts that penn mentioned too, but it took a fair bit of research to narrow down my choices to the four that I mentioned in my original post. I am trying not to be closed to new ideas given the relatively dry subject matter I deal with.

Have a look at Type-Together, esp. at Sirba, Skolar, Capitolium 2, Coranto 2. Have a look fontfont.com, esp. at Milo Serif, More, Page Serif, Tisa, Scala. Have a look at Greta Text from Typotheque.

I do not work with typography or graphic design, so I do not have professional experience in that area.

Maybe something to think about: As TimesNR is everywhere the “transitional” serif model (the genre of Times) might be seen as the most neutral serif model, therefore it might be a good idea to go with Mercury. Other than that, I did read here that slabs stand for a certain conservative reliability, so Brioni would be a good choice too. In my opinion Hoefler Text as an “old style” serif model is too literary.

Best.

oldnick is quite right. From your posts it seems like you are looking for a transitional face, or at least something quite neutral and “academic”. I tend to consider Fleischmans (Mercury is a contemporary reintepretation, but perhaps a bit too polished?) a category of it’s own. Although they were made for book printing (I have a beautiful book from 1805 typeset in Fleischman), there’s more “sparkle” on the page then with a typical old style face, so it might work for your use. I’d like to suggest Kent Lew’s Whitman as another option.

If you manage to make a shortlist (consider personal taste, technical requirements &c), I strongly suggest you get hold of printed samples—ideally produced with the same printer as your technical reports—to compare them IRL.

Another thing: Don’t get sucked in to the gazillion weights hysteria! Consider what you really need.

Celeste, a contemporary reinterpretation of the Transitional heritage, by Christopher Burke, seems an appropriate choice for your needs - text settings for reports instead of, say, novels or more "literary" oriented publications. I have read a book set in it (an essay on Tschichold, by Burke himself), set in a large format, in two columns, and it worked nicely.

http://www.hiberniatype.com/Celeste/celesteregular.html

I also agree with Frode's general considerations and suggestion about Whitman - an excellent typeface:

http://www.kentlew.com/WhitmanOverview.html

Here’s the Fleischman I was talking about.

I also recommend Kent Lew’s Whitman. Its versatile, I own it, and I love it.

I am looking to purchase at least three, possibly four decent fonts.
Since price is a consideration, if you can't afford four decent fonts, then settle for two. Two decent fonts are way better than four less satisfactory fonts, and you'll never regret your purchase.

I would definitely look at:

Lyon Text
Harriet Text
FF Clifford
Laurentian
Rongel
Antwerp

Thanks to everyone who has contributed, I really appreciate it. First rate suggestions from everyone.