Sleep in Vicenza or Padua
 

We only have two days to see these two cities on our way to Venice. Which deserves more time and which sould we select for lodging?

I really enjoy Padova's old town, but the architecture in Vicenza is hard to beat. I suggest spending your night in Vicenza. Good luck.

I can't comment on Vicenza but we found 2 nights in Padua not enough.

I spent a whole week in Padua and while I did day trips most days, I spent a couple whole days (plus all the other evenings) in Padua and loved it. Plan to go back. Vicenza was Ok bu I felt I'd had enough after about half a day.

Difficult choice. Vicenza is way more beautiful, but also way more boring as far as urban life. And one of those rare Italian places where it's rather difficult to get a more-than-just-decent meal in the evening. Padova is a university town, thus with plenty of students, and a far less calm & distinguished atmosphere than Vicenza. It's perfectly possible to see the main sights of both towns in one day each.