Well that depends on your preferences. If you would like to enjoy privacy, comfort & hospitality then I would say that go for 1 AC coupe. But if you feel that a journey is better when you interact with your fellow passengers, then go for 2 lower berths in a compartment because it will take close to 25 hours. And that's a pretty good amount of time. And add to the fact that your train will cover the maximum part in daytime so that also gives you a great opportunity to enjoy the countryside, the same reason because of which I prefer day journeys & hate night journeys.