A year ago, Conde Nast published an article titled, "10 Best Small Towns to Live in America". A friend of mine recently put a link to it on her Facebook page, which was the way in which I learned of its existence.
The first thought I had was, "Hmm... The title indicates that the story is about best small towns that are living in America, and not about the best small American towns in which to live." The verb to live can be used as part of a verb phrase (i.e., to live in) or independently (i.e., to live in America), but it cannot do both things at the same time. Therefore, the syntax of the title requires the interpretation of "10 best small towns to live in America," or - to repeat my thought - that the story is about best small towns that are living in America. Which is an awkward concept, unless you're writing a piece of fiction, in which small towns are conscious entities.
Furthermore, as an adjective, "best" indicates the ultimate of something; it has no superior (as opposed to adjectives ending with "-er" or adjective phrases using "more"; never mind the Hawai'ian patois use of "more better"). Thus it requires the use of "the." Saying that it's a headline would be a good excuse, save for the problem that the whole point of abbreviated headline grammar is due to the exigencies of space-saving; something that is next-to-unnecessary when publishing online. So, to make the minimal number of changes, the title ought to read:
"The 10 Best Small Towns to Live in in America."
True, this title is grammatically correct, but awkward due to two different uses to which "in" has been used: one as part of a verb phrase ("live in") and one as part of a prepositional phrase ("in America."). Furthermore, if you don't like verb phrase constructions (i.e., if you hold on to the 18th Century English grammarian's notion of "correct" grammar mimicking Latin/Romance grammar), then the easiest "fix" is to change the word order (and grammar) to make the sentence mimic a Romance-language construction, thusly:
"The 10 Best Small Towns in which to Live in America."
"The 10 Best Small Towns in America in which to Live."
Of course, either of these constructions is rather awkward to the modern American reader, for whom the use of phrases like "in which" are dying (much like the distinction between who and whom). Therefore, another editing option would be to change the verb phrase (to live) for a single verb that has the same (or very similar) meaning and doesn't rely on being a verb phrase in order to hold that same meaning (I prefer "inhabit" among all the options):
"The 10 Best Small Towns to Inhabit in America."
Well, upon reflection, that just sounds awkward for a whole different reason: inherent meaning. While to inhabit and to live in do mean effectively the same thing, the feelings evoked by the words are different. To quote Winston Churchill - as quoted in by Romm in Language Intelligence - "All the speeches of great English rhetoricians ... display a uniform preference for short, homely words of common usage." The same is true with catchy headlines, I suppose.
Ergo, whilst it may behoove the author to adhere to appropriate grammar structure and diction whilst composing, a successful application of such adherence would obfuscate their topics of dissertation from those who desire to acquire the insights of said author. Or - to put it another way - don't be fancy when you don't have to be. So maybe a better title could be something like:
"10 Great American Small Towns to Live In."