https://corplinguistics.wordpress.com/2013/06/21/the-weirdest-languages/
And the weirdest, by their methods, is 'Chalcatongo Mixtec' spoken by around 6,000 people in Oaxaca, Mexico. And to get to that point it is
- tonal, which marks it as slightly weird (very approx 40% of languages)
- verb-initial (very approx 8%)
- Yes/no question sentences are not distinguished from statements either by word order, use of a 'question participle' somewhere in the sentence, change of intonation, or, indeed anything (1 out of the 954 languages in the study). 'I am the only person on this forum unable to my head round this'.
- Something odd with 'proniminal subjects' combining the, eg, Spanish/Italian method (subject markers modifying the verb), and the, eg, English/German method ('he','it', 'they'), but in the latter the pronoun does not appear in the same position as the full noun phrase would appear (again Chalcatongo Mixtec is the only one).
Whereas Basque, a language isolate, is 10th least weird. Weird.