I think it's up to individual . Not so right to compare a prime and a zoom lens here . Both serve different purpose . I got both .
For 17-50mm it's really a very versatile lens . Infact it should cover most of Yr shot with this fl. Beside it's 2.8 very useful even if low light condition . For event , it work great too.
Da 35 f2.4 was top iq with the given size and weight . If you want to travel light for the day , you wouldn't want to bring the Tammy out. Beside using prime will train on Yr composition more . Lastly , it's going so cheap now and I dun think need to consider much by just owning one to use .
I bought the tammy 1st then the da35 f2.4pm thinking to replace the tammy . But at the end of the day I just love them both and decided to keep both . As both serve me differently .