I own AirPods Max and AirPods Pro (1st Gen), the max are my preferred headphones for listing while working while the latter are best for exercise, running errands, etc.
The active noise cancelling (ANC) on the Max is hard to to exaggerate, it works that well (esp. in noisy L.A.). My Pros are great but the ANC can't hold a candle to the Max, maybe the Pro 2s are better but I wouldn't know.
For telephone calls, I often use the AirPods Pro because I can get away with one earbud instead of wearing the whole thing but for important-ish calls, I will often use the AirPods Max because of the ANC. For international calls, assuming you're using POTS and not FaceTime Audio or Skype, I don't imagine you're going to see any improvement over a typical phone call.
For video/Zoom calls, the Max are a dream. The longest I've gone wearing them in one session was a little over 3 hours and they were quite comfortable. The Pros often get "itchy" in my ears after an hour or so and I need to take them out, wipe them with a Kleenex, then pop them back in. The Pros usually last quite well on battery but run out of juice after about 2.5-3 hours on calls while the Max can go on and on. I like that I can charge the Max while wearing them, that's a nice advantage if you're low on battery.
Candidly, I don't know how much more "improvement" one could have over the current gen Max. I bought mine at the Store (hello 3% cash rewards!) but you may be able to find them online in other stores for a discount.