Which of these languages is the least logical?

[angus]

Among those, I might tend to agree with you if I had more knowledge of French.  English is my native language.  Also, I lived in Germany for a year and studied German for about six months before living there, so I have some familiarity with that language.  I studied Spanish for many years in high school and university and have worked as a Spanish/English interpreter and have traveled extensively in at least 12 hispanic countries, so I am also quite familiar with the Spanish language.  Among those three, I'd agree that English is the least logical.  English, for example, has at least two words for everything.  One Latin, and one German.  (We get our German roots largely from migrants from Jutland, by the way )  Take Free, for example.  We say Liberty--like Liberta in Italian, Liberté in French, Libertad in Spanish, etc.--but we also say Freedom, like Freiheit in German, or Frihed in Danish.  Also, we usually arrange our verbs like the Latin languages, but we can keep them at the end, like they do in German, especially if you're Yoda or a Yiddish New Yorker:  e.g., "A real comedian, you are."

As for French, I have very limited understanding of that language.  I know enough to order a beer in a bar in Paris, or ask where the restroom is, and I can say things like "how much does that cost?" and "we have a reservation for three under the name of angus" but I really can't keep up a serious conversation in French.  French pretty much sounds like you have a big hacker caught in your throat and can't quite cough it up.  Other than that, I know little of the French language.  Therefore, since French is one of the options I cannot vote in this poll, but among the three languages you listed with which I am familiar, English seems terribly illogical.  Especially spelling rules in English.  Don't even get me started on spelling.  English spelling is a beast.

There is a linguistics expert who posts here regularly.  His handle is Ilikeverin.  Maybe he will chime in and give us his expert opinion regarding the illogic of languages.  I suspect that the newer a language is, the less logical (and more technical) it will be.  Chinese, therefore, will be very logical.  English, on the other hand, will be very illogical.  "Is there an app for that?" sounds pretty stupid, but actually has a very precise meaning.  The phrase evolved somewhere in the vicinity of San Francisco--a relatively recent city with a spanish name in which most of the residents speak either English or some variant of Chinese--but a phrase which probably sounds pretty much the same in just about every known language.  What does a Sherpa call an app, anyway?  My guess is, an app.

[angus]

"split infinitives"

We split them only because we can, and there's no reason that we shouldn't.  In those other three languages, it is impossible.  I like to regularly split them.  (see, I just did it.)

[angus]

The Romance languages suck at hypotheticals though and that's important to have.

Really?  I guess I never noticed that in Spanish.  I'm looking at a Spanish chemical physics text just now, published in Bilbao, and I'm reading the section on Planck's Distribution Law.  It is full of hypothetical statements, conditionals, and suppositions and none of it seems strained or awkward.  In some cases this is achieved with verb conjugation, but mostly it is achieved with what are called conjunctions in the English language, but which are called preposiciónes in Spanish since the "conjunction" doesn't exist as a separate category in Spanish.  

The derivation starts by asking us to imagine a collection of N oscillators, each with the same fundamental vibrational frequency, and walks through the standard derivation and ends up with the same algebraic form of Planck's Law found in English-language textbooks.  It even goes on to refer the reader, in a rather long footnote, to note that if the exponential term in the denominator is expanded as a Taylor-Maclaurin series in frequency and ignore the higher-order terms (which is justifiable for sufficiently long wavelengths), then Planck's Law collapses to the Rayleigh-Jeans Law.  

If I flip over to the section covering atomic structure, I see that the postulates of quantum mechanics are described pretty much as they are in English, and they do not seem strained or awkward either, even though conditionals and hypotheticals are used.  Interestingly, they do not capitalize the H when writing out Hamiltonian operator.  They just say that "Ĥ es el operador hamiltoniano..."  I think I have noticed that before about Spanish.  Adjectives are not capitalized, if they came from proper nouns.