Indigo airlines is one of the largest operators of the A320neo, and have now bought 150 A321 neo’s. (They are also eyeing the A330neo, but haven’t ordered them yet.) I have flown with them multiple times, including the A320neo’s and had an overall enjoyable experience with them.
For anyone interested, here’s Josh Cahill’s review on Indigo airlines:
I actually can spot one major difference between the normal A321 and the A321NEO, there is no door in front of the wing, there are two small doors over the wing instead
IndiGo is the largest operator of the A320N and one of the, if not, the largest operator of the A321N. It has also placed an order for 300+ A321N. Would definitely love to see this livery in IF. You got my vote!