What is the best choose...Uber is cheaper but they can kill you and on the other hand, taxi standard doesn't kill you but are unsafe, unfair, unpolite and disonest?
Standard taxis are fairly decent, if you're fairly decent.
Uber is cheaper and generally ok, again as long as you're sensible.
If you feel unsafe in either situation, get on the phone and talk (or pretend to talk) with someone. That is a huge discouragement to potential violence. (And in general, let friends know where you are/what you're doing.)
If you suspect someone of cheating you, smile and walk away. Don't confront. You will never win in a situation in which face is involved.