A new airliner which is not a Boeing or a ‘Bus might help ease carry-on conditions for travelers in a few years:
The plane (Bombardier C Series) will also be very comfortable as a passenger. Seats will be in a 2-3 across configuration and each seat will be about a half inch wider than on an Airbus and more than an inch wider than a 737. The overhead bins will be big enough to accommodate roller bags for 90% of the passengers onboard, which is ample room. - Cranky Flier
This begs the question: How does this plane’s bin space compare to current planes? This is hard to say since there are multiple versions and configurations of each common airliner. Which planes pose the most trouble for you as a carry-on traveler? Which airlines?