Computer Modern, the typeface built for TeX using Metafont that gives academic and research papers that signature, serious look, was designed by Donald Knuth with the guidance and advice from Hermann Zapf.
I remarked to Knuth after a Stanford talk several years ago how great CM was. He told me to thank the woman in front of me who was a calligrapher for him in the '70s. I never caught her name, but I was chatting with her right before that. I think he actually had a few students working on it.
I don't know, a lot of people I've met ditched CM for Times long ago because you can squeeze a lot more text in, which matters for conference publication page limits.
I find CM a bit boring because of how pervasive it is in math and science papers, and it really doesn’t work well with some types of documents, but Times is almost always awful, with only few exceptions. In particular, most of the commercially available computer Times typefaces have crappy kerning, are missing typographic features (ligatures, fractions, small caps, etc.), often have awful glyphs for common symbols (especially @, ugh), have a limited number of fonts optimized for particular sizes and uses. In general, Times has a very inconsistent look from one letter to another (w/t/t the stroke angle and various letter forms) and results in uneven and distracting text. I find it to be quite unpleasant in contexts like books or academic papers. Moreover, it is still very much overused.
Using Times in a document implies to the reader that the author/typesetter either doesn’t care very much about typography or is being pushed around by some overbearing external style guide or clueless client. In the latter case, it is possible to use Times well and produce workable documents, but it takes a lot of extra hard work on the part of the typesetter.
If your only goal is to fit more text in, there are dozens of better choices.
Okay, so what's a drop in replacement for Times that comes with standard LaTeX distributions? It must fit as much or more text and ACM must be okay with it.
Reviewers will actually criticize authors for using CM, preferring to have the extra information.
There's Matthew Carter's great Charter, which is free to use and on CTAN. You might have to decrease the font-size a little to match TNR's space efficiency.
The best font in the world is included in LaTeX: New Century Schoolbook.
Don't let the name fool you, the font is optimised for readability which means you can drop the font size and it will still be easier to read than CM at a higher font size but you get more space to work with.
I am not familiar with the ACM’s style guidelines, sorry. I assume most ACM journals are going to have professional typesetters fix up documents to match the journal style, so if you’re just talking about what typeface to use in a draft/preprint, it won’t make it through to the final published paper anyway, so it probably doesn’t matter much. For conference proceedings, I dunno.. maybe make one version for the conference matching the style guidelines, and then a prettier version to host on your own webpage?
Yes for journals, but most CS papers are published at conferences. Depending on the conference, not every paper uses the same typeface - except, most people use Times because it is space-efficient.
Anyway, forget about ACM. What's as space-efficient as Times and also prettier?
I’m a fan of Slimbach’s typeface Minion, which is quite compact and looks sharp in most any context where Times would be appropriate, but doesn’t call any special attention to itself. A version typically comes with any Adobe Pro apps from the past decade at least, and in some cases is the default typeface I believe. Minion is therefore also quite overused, but not as bad IMO as Times or CM, and it’s much easier to make a good looking document with than Times is.
CM is a damn nice typeface, far better than Times in my opinion. Just because people started using bad typography in order to appeal to some silly rule doesn't mean CM is any worse of a face.