Red dot optic for pistol

Have the SIG Zero Sight and it seems OK. Shake-awake, multi power levels and zeroes pretty easily. The key to using it quick is to draw and bring the pistol somewhat close to your eye to pick up the dot quickly. Press the pistol to the target as you are depressing the trigger.

Mounted one of these on my Glock custom. 
https://www.cyeleeoptics.com/products/wolf0-rugged-pistol-shake-awake-red-dot

Shake awake, top battery access, long battery life.  only downside is needs a mounting plate and taller front and rear sights for a back up. Lower intensity on red dot makes it easier to square up in darker situations.

You can spend more but why?

Those type sights are great especially for our aged eyes. They do break, batteries die, etc. so be sure to keep proficient w/iron sights too. Find one that has red & green. You can't  see red in daylight. The green is good in day or night.