156, but WELCHER?

Hi You, I’m playing with the thought of maybe getting a used 156, but which one should you take! (1.6 , 1.8 , 2.0) Which one is the one you can most recommend, and which one holds the longest! What problems does it have/does such a thing? Have you heard that with ALFA often the electrics should spin and is just very unreliable! How much truth is there? What should one pay attention to when buying? Be happy about every answer!