The 737's the world's most popular airliner
Yes it is. At the same time it as been many years now since more A320 family airplanes are sold per year than the B737 family...
So this airplane has lasted for sure, but in the world that is not the airplane the airlines like the most nowadays.
At the same time comparing the B737 100 (or even 200) with the nowadays popular B737 800 is ridiculous.
Not the same engine, not the same technology, not the same instruments, not the same size... It is not the same airplane. Only the name, and the shape.
There is more difference between the B737-100 and B737-800 than between the Airbus 320 and the Sukhoi 100 superjet.
Anyway I like the B737, I think pilots like it more than the airlines, airbus being more cost efficient, more convenient to carry cargo, more convenient to train crew on the other airbus family aircraft...
It is still a simple and standard airplane with conventional control commands, systems, twin engine, no fly by wire like the bigger boeing or airbus, and flying it really isn' t much different than flying a much smaller airplane, and I like it.