Padua and Verona

I don't think it would be very fun to do both in one day. I've done each one as a day trip from Venice. I preferred Verona - it was very walkable, quite charming and had sites that were easy to get to on foot - we walked from and back to the train station and were able to navigate ourselves around easily, which isn't always the case on a day trip.

Padua is closer, has a street tram from the train station to the city center and the main sites, Scrovegni Chapel (must have advance reservation, on-line or phone), University of Padua with the famous anatomy theater, central square markets, Shrine of St Anthony.
Its a day trip.

I've visited both and like both. I would not recommend both on one day. Each merits more time than that. If I had to choose one I would pick Verona. Both are very easy to navigate from the train station.

Been to both. We did Padua as a daytrip when we were going from Venice to Verona. For you, I would also recommend Padua (Padova in Italian).

I agree with the others. Either one is a nice day trip (although I spent 3 nights in Padua with a daytrip to Ferrara, and one night in Verona). But don't try to see both in 1 day - too much.

Which do I recommend? They're both good, so pick whichever one interests you more. Read about them in Rick's book, and see them in the video here: https://www.ricksteves.com/watch-read-listen/video/tv-show/season-8/italys-veneto-verona-padua-and-ravenna.

Both in one day will simply be too much. Either one can consume an entire day or more. Research both and pick the one that holds the most appeal for you.

I have a definite preference for Verona and I think there's more to see there. The Arena is a must. It does take longer to get there from Venice by train, then bus to the historic center or a short taxi ride - it's just a little too far for walking. Google Verona Card for a list of sights - skip Juliet's house but go up the tower.