Basicity af N containing aromatic species

Hello friends, I got struck in this interesting question on basicity. I am able to get different answers applying different methods. In general, for these compounds we have to see the lone pair denoting tendency by the nitrogen. I was able to conclude that IV is most basic. And II is greater than I. Now the problem is between I and III. Whether to consider the -I effect of $$\ce{N}$$ or $$\ce{Ph}$$ more effective? And, is -I the correct way to compare among both of these? I even draw the resonating structures but was unable to conclude anything from there. Please help as to how to proceed.

• (This might be cheating but will help any answerers). The pKa' values (pKa of conjugate acid) of pyrimidine (I) and quinoline (III) are 1.10 and 4.85 respectively. (Source: Wikipedia pages). This suggests III is more basic as it attacks $\ce{H+}$ at a lower $[\ce{H+}]$ concentration. – Eashaan Godbole May 7 '19 at 17:51
• – Mithoron May 7 '19 at 19:58
• @Mithoron unfortunately, a vs b and a vs c together don’t make duplicates of b vs c. That said, I am of the opinion that there is no way to answer this with beyond stating that, solely based on empirical evidence and experience, an extra nitrogen in the ring is more electron-withdrawing than a fused benzene ring. The proof is in the pKa values. – orthocresol May 8 '19 at 1:43
• @orthocresol So I voted for too broad, but q. was kicked from queue because of edit that only corrected spelling... – Mithoron May 8 '19 at 15:31