The MC34063 is by far better than the TL497, the following are some highlighted reasons:
1- The OP transistors of the MC34063 are (Darlington configuration) and that prevents the transistor from being driven into hard saturation. (hard saturation will shorten the OFF time).
2- Wider IP voltage range (up to 40V MAX) vs. 15V for the TL497 (note that it differs from the OP voltage).
3- The MC34063 has smaller footprint (comparing DIP's).
4- The MC34063 is newer than the TL497 (TL497 introduced 1976 I guess)
5- The MC34063 is cheaper as it has been manufactured by more than 10 Manufacturers
6- OP Ipeak is 1.5A, twice of what the TL497 can offer.
and finally, the MC34063 is supported by Proteus VSM while the TL497 is not, good enough reason for me ...