I’ve just done some test on different RF433 receivers, from the classical really low cost system to some more expensive systems. The test environment was always the same : a dirty test board with lots of wire connections everywhere and an antenna made with a 17.3 cm wire. The conditions are poor but identical.
Then I move around my house and activate my alarm detector one after one and check if the system received it. Some detector are same floor, 1 floor or 2 floors distance, some are behind walls, distance vary from 5 to 20 meters in house.
The following results are the number of message received by the different receivers in this context. More you see, better it is.