What’s better to read from when leining the Haftorah. Navi written on Klaf that has in it pasulim or from a Chumash?
It is better to read from the kelaf.
According to many authorities, a sefer torah that has a pesul is still considered a kosher sefer torah, and this of course applies to a kelaf of nevi’im too, so that there is a virtue of reading from the kelaf.
This is the opinion of Tosafos (Megillah 9) and the Ran (5b), who write that the pesul for a sefer torah is a halachah in reading the Torah, and not in the sefer itself.
However, according to the Ramban (Megillah 17), Rashba (1:611) and Gra, a pesul in a sefer torah invalidates the actual sefer, and according to this, the kelaf will only have the virtue of a sifra d’aftarta.
Yet, some poskim write that a sifra d’aftarta is better than a chumash (see Aruch Hashulchan 284; Halichos Shlomo 14:33), though others write that it does not have any special virtue (see Shaarei Efraim 9:10; Chazon Ish 60:10; Rav Pe’alim 20:33).
Thus, it is better to use the kelaf.