... which would it be?

Alll depends on your interests
...and on your itinerary

none in the sense that I would never plan a trip to a city mainly to see a Roman ruin. I'm just not that interested in old Roman ruins, I've seen them umpteen times all over.

Those are all considered excellent specimens of Roman arenas and well-preserved. So I'd decide based on what all I wanted to do in that town, not just on the Roman arena. I've seen them all but what sticks out in my mind from those visits are the other things I enjoyed, not the amphitheatre. Except maybe Orange, I really liked that one but I also hit the town on a day of a street market that was quite good. Nimes of course has an excellent example of a Roman temple, also, if you are into that stuff. Both Nimes and Arles have some museum about Roman ruins, I think.

I've visited the one in Orange twice. Both times it was obscured by stage props.

I prefer Arles over Nimes. Nimes might have more Roman Ruins, but I found Arles to be a more interesting city. Good museum there also.

Stu Dudley

Haven't been to Orange, but did visit both Nimes and Arles. As I recall, the one in Nimes was larger and better preserved, but both were interesting and both cities have excellent museums of the Roman era.

The amphitheater in Nīmes is very well preserved. I haven't seen the others. Near Nīmes you can also visit the Pont du Gard, a very beautiful and well-preserved Roman aqueduct. We took a bus there from Nīmes. There are various other side trips you can make from Nīmes; for some of them a car would be better.

I've only seen the one in Arles, and I enjoyed it. I agree with Stu, Arles is a nice city to explore. The Arles arena is featured in the movie: Ronin, just a little trivia...

Yea I knew there's a general consensus that Arles is a more charming town but there's surprisingly little comparing their respective amphitheatres.

I've been to them all, several times over. I love them all. However, I tend to favor Orange, but it can depend upon what time of year you are visiting and what 'events' might be taking place at Orange. Big events can change the look and feel of the site.

Which, after Orange, takes your second place vote?

Have you looked at the photos online? If you Google them, you can get a pretty good feel for what they're like. Is there anything else you want to do while you're there? Those would be other considerations.

Arles has perhaps the best preserved arena, but the size of Orange is more impressive, even though it is just a half circle. This said, Nimes has the most Roman sites that impress, including the Maison Carrée, which might be the best preserved Roman temple in the world. This doesn't help you decide at all, does it?

Just so you know: there are others, of lesser reknown: Vaison la Romaine, for one; another in Burgundy, I forget where...was it Autun?

The theatre in Vaison is very unremarkable.

Stu Dudley

For me, second favorite would be Nīmes, mainly because there are several major sites that can be visited by foot in one day. All of which are nice, IMO. All of which can be reached by foot from the train station. But again, if there are events taking place, especially in the Arčnes, it changes the look of the site and can change the accessibility of the site too. To me, it is a good idea to check what may be taking place at any of the mentioned sites prior to making your plans.

https://www.thecrazytourist.com/15-b...-nimes-france/

I never became blasé when seeing the amphitheatre in Nimes nearly everyday. The Maison Carree is fabulous to look at from the outside ( especially sitting at the restaurant opposite), and worth noting that inside is like being at a movie theatre as you watch a video. I was surprised as I expected the inside to be restored as well. A classic mistake on my part for not doing full research.

I absolutely loved the one at Orange. Had a lot more ambience than Nimes or Arles.

Arles during the Féria du Riz which will take place from September 6 to 8 this year in Arles.

Good advice. Turns out there's a Dua Lipa concert at the Nīmes amphi just 4 days after our planned visit. I'm guessing they'll already have all the concert infrastructure in place by the time I get there. So we'll do Arles instead.