In my time of need quest skyrim should I help Saadia or Kematu? (Spoilers)

[Jupiter]

am doing the quest "In My Time of Need" in elder scrolls V Skyrim

An Alik'r warrior had asked me to find information on a redguard woman they are after.

I found her in the Bannered Mare inn

but she says she is a noble and wants me to help her and kill a mercenary leader called Kematu

not sure what to do? Go with Saadia or Kematu?

[Sphinx]

According to the In My Time of Need walkthrough

it's better to side with Kematu