What handgun and in what chambering and how much do you want to spend?

Red dots are like scopes. Usually you get what you pay for.

Aimpoint and eotech are two of very good quality that will stand up to big recoil.

Zeiss also makes a very compact red dot that has dual power, solar and lithium battery. The battery isn't used unless there isn't sufficient light for the solar panel thus greatly extending battery life.