Connection at Dulles or Newark?

Go with Newark. United's hub is under one roof in terminal C; so it very easy to connect between domestic and international flights. They are not segregated in any way, it's conceivable that when your Orlando flight arrives the flight to Paris could be the next gate over.
Some of United's commuter flights use terminal A, but that is unlikely with an Orlando flight.

Double check Newark's website to ensure the current runway reconstruction will be complete by May. There are a lot of late flights into and out of Newark at the present time.

I say Dulles...

Dulles...nicer airport, better food (if open). I found Newark to be really unmemorable except for the poor dining options. The only upside is you can see Manhattan from the air when you take off or land.

https://www.nj.com/news/2021/09/work-finished-early-on-runway-that-handles-half-of-newark-airport-traffic.html

Looks like the worst of the construction delays are over at Newark

poor dining options

That is certainly the case at the other two older terminals. But at terminal C where United operates out of, the dining option are considered some of the best of any airport in the US:

https://www.northjersey.com/story/life/food/2019/09/12/newark-airport-terminal-c-named-best-foodies-dining-guide/2145701001/

Thanks, I’m leaning towards Dulles as it is currently a few hundred dollars cheaper than Newark.

This has just become a no-brainer. IAD is easy, spacious and usually problem-free. Think of all the Hudson News gummy bears you can buy with that extra $$$.

I must be confused, Dulles is backwards from Orlando to Paris by several hours? Can you check flights from Mami? I would think you could fly Miami to Paris direct. As far as which airport is better I like Dulles over Newark. I guess my question is: do you have to fly Delta or can you use British Airways (will conect in London) or can you use Air France? I would take a look at flights from Miami as that is a bigger airport than Orlando. I live on the west coast, I use SFO or LAX to get overseas and take a comuter flight to LAX and drive to SFO. If I try to fly out of my local airport I would need to hop-skip and jump arcoss the USA.

MCO-IAD-CDG is only a 112 miles more than MCO-CDG

" I guess my question is: do you have to fly Delta or can you use British Airways (will conect in London) or can you use Air France?"
Odd question given that the OP says they are flying on United.
"I must be confused, Dulles is backwards from Orlando to Paris by several hours?"
No, not really. Are you perhaps thinking of IAH (Houston)?

@Simpgolf, I've connected through both IAD and EWR and fly into EWR 3-5 times per year to visit New York. The food is pretty good at Concourse C at Newark but go with the cheaper flight as long as you have enough transfer time. Neither airport is worth the effort of picking one over the other for anything but price and transfer time.

No, not really. Are you perhaps thinking of IAH (Houston)?

Maybe they read it as "Dallas"?

Good point.