Which sensor is best for obstacle detecting with retroreflector? Distance is about 3m. IR or visible light - does not matter.

It is possible that object/obstacle can be shiny, so for correct detection necessary large amount of reflected light.

Maybe for this task better to use specific retroreflector?

UPDATE:

there will be two sensors with distance about 3-4 cm between.
Object must cross 1st sensor's reflector but do not cross the 2nd one.

The scheme of this sensor should be this:


But the use will be this:
I think the question is worded to get a specific answer; I do not know if this is the answer you want. I'll give you that answer first:

I'd say an infrared LED, and an infrared detector.

Strobe the LED, then measure the difference between when it's (known to be) on, and when it's (known to be) off, to compensate for ambient light.

However, if I was doing this, I'd consider an ultrasound sensor - no retroreflector needed; instead you get the distance to the (obstacle or reflector).