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:
here’s some more information about Indigo: IndiGo - Wikipedia
Credits to Deirk Weinrich
Hope this gets added soon!