The numbers, the longevity, and the usability say it all. It may have won many of its orders over recent years because Airbus was booked up on the A320, but it had to be at least decent to stay in the contest there. And will it stay in production longer than the A320: yes, of course it will.
An aircraft is the sum of the metal and plastic that go to manufacturing it, plus the design and mangement brains behind it that come up with a cost effective product that hits the spot profitably, and a sales force that understands customers. The 737 was not a special ground breaker in the former, but it was in the latter. For me, the world's first global bus, and a key reason for the success of commercial aviation from the 70s on.
Ebeezeer Scrooge says:
I agree with your choice, and those who prefer more esoteric airliners like the Concord have probably flown on more 737s than on their preffered choice. Ironic really.