Which indicator is most suitable for the titration of aqueous ammonia against hydrochloric acid?

The equivalence point of a weak base with a strong acid lies on the acidic side (the salt $\mathrm{NH}{}_4\mathrm{Cl}$ hydrolyses to give an acidic solution), so an indicator changing colour in the acidic range, such as methyl orange (pH 3.1-4.4), is suitable. Phenolphthalein (pH 8.3-10) changes colour long before the equivalence point.