I think Boeing is busy trying to keep their dual isle 787's from turning into Roman Candles right now. I think a single isle option is a low priority. LOL
I am more a fan of Boeing, but I do have to hand it to Airbus for getting what it does out of a 321. They have really bumped the gross weight up over the years, and put in much more powerful versions of the engines. I heard the original 321's were dogs, but I never flew them. I did fly brand new 321's, 93T MTOW, IAE 2534 engines. 34k lbs of thrust. They were rockets. They also had rocket-like V speeds, but at least they accelerated to those speeds quickly.
I start ground school for 737NG in a couple of weeks. Boeing has gotten more out of them than anyone would have ever guessed as well. We also fly the 737-900ER which has surprisingly good range. But due to the ground clearance the fan size is limited, and they only have a max of 28k per engine. I have heard they are complete dogs. Ground hugging, runway eating, dogs. But brutally efficient, long range, dogs.
My favorite airliner to fly is still a 757.