$\mathrm{NH}{}_3$ ($K_b=1.8\times 10^{-5}$) at $0.10\mathrm{M}$ is titrated with $0.10\mathrm{M}$ HCl, and the equivalence-point pH is $5.28$. Which indicator is best suited?

The indicator range must include the equivalence-point pH ($5.28$, from hydrolysis of $\mathrm{NH}{}_4{}^{+}$). Only methyl red (4.4-6.2) brackets it. Thymol blue (acid range 1.2-2.8) changes colour in a far more acidic region than the equivalence point, while the two phthaleins change colour in the basic region, well past it.