Assisi or Orvieto for a day?

Two completely different experiences - both great in their own way. What are you looking for? Assisi will be pretty much based on St. Francis and St. Claire. There are also Roman and some Etruscan ruins. Orvieto has a beautiful basilica, great shopping areas, Roman and Estruscan ruins. Both cities have spectacular views since they are both quite elevated.

Which would be more crowded?

Both places are amazing, but Assisi clearly was more crowded than Orvieto.
Also, Orvieto is closer to Rome in case you are flying into Rome.

Assisi is always crowded around the Basilica but the upper town is usually very quiet

Same for Orvieto-lots of daytrippers near Duomo but the quiet lanes in town are not usually crowded

Overall I would say Assisi is more crowded -it’s a common stop for large tour groups, Orvieto is not

Assisi is always crowded around the Basilica but the upper town is usually very quiet

Same for Orvieto-lots of daytrippers near Duomo but the quiet lanes in town are not usually crowded

Overall I would say Assisi is more crowded -it’s a common stop for large tour groups, Orvieto is not

Both towns are lovely, so you really can’t go wrong
We have been to Assisi once, Orvieto twice
Assisi is super steep but so is Montepulciano!

The backroad drive from Montepulciano to Orvieto is beautiful and you could see Civita Bagnoreggio (just the view) with a slight detour on your way

It’s been years since we drove Montepulciano to Assisi but I don’t recall the drive as memorable other than the view of Assisi as you approach

I have been to both and wouldn't bother with Assisi unless I had religious reasons.
The Orvieto cathedral is stunning.

Agree, if religious Assisi, and I thought Orvieto was pretty spectacular. Taking the bus up from the train station sit on the right hand side and the views are awesome.

I do believe Orvieto has won. Thanks so much everyone!